And it is important because there are elements of myth (and by extension, good fiction) that are diminished or destroyed as a result of high magic.
Well, first of all myth != good fiction. And good fiction != good game.
Okay, let's see here, let's do The Odyssey, but within the confines of D&D rules....first, let's do the 'crucial elements of the story.'
#1: Odysseus is a sneaky fighter who has won a great war, and wants to get home. His defining trait is his cunning and wit.
#2: Posseidon has a vested interest in making Odysseus & crew go through a long, obnoxious route to get home.
#3: Through a series of stops on the way, Odysseus is jerked around by some gods, and gets home. Those stops are the adventures in the campaign.
Now, to D&D-ify:
1) Well, since we have (let's say) 5 players, we'll need 4 main characters. So let's say Odysseus (sneaky fighter) had three of his heroic buds along for the ride: Jozan, Kyrrwyn, Mialee, and Regdar. Yes, I know they don't sound Greek, but that's hardly a problem with the d20 levle of magic.

2) The Trojan War just ended. In it, the Achean fleet and their heroes invaded Troy, killed their people, and took their stuff. So these guys can't be first level -- let's make 'em 15th (hey, they're heroes!), and the GP they get to spend on character wealth is a combination of the equipment they've braught with them to fight, and the stuff they've found on the battlefield. Maybe their +3 greatsword is maybe Trojan-made...Mialee raided the temple to Hecate and got a few handy spells to cast, maybe even a few 8th level ones.
3) They want to get home, and but Troy is more than 1500 miles from Ithica (Teleport don't work, and, yes I know that isn't historically accurate, but that really doesn't matter, it doesn't destroy verisimilitude), and besides, they've got a crew of mooks (of varying levels, most below LV 12) to get home. They get out to sea, but a storm strikes and starts to blow them off course. Jozan, Great Cleric that he is, has remembered to prepare
Control Weather and casts it. He offers a prayer to the god of storms, Zeus, and Zeus, taking a shining to ol' Jozan, tells Posseidon to knock it off for a bit. Of course, Possiedon doesn't like it, and so, using the same tools at his disposal, he has his merfolk druids in the area run a bit of interference -- counterspells galore, and a force of druids has more ammo than a lone cleric on a ship. Victory, Possiedon! But the party gets some XP for it, and gets sent to their next location, storm and all.
4) Probably for good measure, some aquatic monster attacks, maybe specifically targeting Jozan. You don't get to test the gods and get away with it that easily! By now, the PC's are aware they're in no natural circumstances. Risk +, fear + -- they've got a god who hates 'em, and only one healer amongst them! But the god didn't just smash 'em out right....so what's next?
5) They get blown to an island where the people are all at rest and at ease, lethargic and eatin' lotus. No one has ever left here before (dun dun duuuuun!), but the PC's, and a handful of crew members, manage to be some of the lucky ones -- because of their massive skill vs. the DC 25 potion, and the handful of higher-level shipmates/natural 20 saves. Epic adventure+! They've done something Unique in the World! They probably fight off drug-crazed cultists and their Mind Flayer leader, who is providing the drugs. Maybe they even liberate a few there, while they're chillin'. Adventure 1.
6) They want to get home, so they use a bit of divination.They can't scry on their homes (any king worth his salt isn't going to allow some perv with a crystal ball access to MeTV), but that's why they've stationed mooks outside, so they can see what's up. According to the Mooks, it is all good. A bit of
find the path gets the quickest route home, and they go for it...
7) Possiedon blows them away as above, and sends another monster down their throats.....mooks are dying in droves because they keep attracting big sea creatures. Sacrifice, Bad Consequences +++! The PC's probably realize a God can't be faught, and decide that further "just trying to get home" is pointless....they decide to ride it out, and do what they can to help the wounded. For good measure, Jozan does one of those oh-so-destrutive divinations to find out "should I continue to try and get directly home?" magic-8-ball-god says "Outlook not so good." Crap.
8) Maybe they land at a few more islands, some with dungeons, some with natural disasters, most just with big monsters they can put an end to in stylish fashion to save the city. But they're still so far from home.....and what's worse is that now Mialee's divinations on the Mook are coming up negative....the mook has died, and they can't see into thier house anymore. Magic 8-ball deity says "Try Again Later." (Zeus doesn't want to irk Possiedon anymore, and agrees that the mortals need to learn their lesson). Mystery, Suspense ++! They'd teleport/island-hop, but they've still got their own lower-level goons to transport home, and Mialee's not interested at all in fetch-teleporting, since the most reliable description of the neighboring island she can get is from the old codger of the island who says something like "stupid neighboring island with it's evil barbaric ways!" Stupid insular city states and strange, strange locales not interacting!
9) AAAAH! CYCLOPS! Since the sea monsters destroyed some of the ships, and
create food and water won't fill the stomachs of these couple of hundred people with Jozan alone, or the other few mooks who can cast it (there were about three clerics per ship, but after attrition, they're down to about three clerics. Period.), they need to raid the island for some chow. Slow Depletion of Resources ++! BUT, of course there is a monster guarding even this treasure, and being a banished half-deity (paragon), taking him on single-handedly ain't really an option. BUT, Odysseus rolls a good Knowledge (children of the Gods) check, and determines that this guy digs the alcohol. Getting a CR 20+ creature drunk is no mean feat, but it helps that Odysseus's Charisma is flabbergasting (and people call it a dump stat!). Clever Odysseus weasels the half-deity out of his sheep, gouges out his eyes, and runs away, taunting the entire time. Of course, even blinded, the creature put up a fight, and not everyone got out alive (poor Regdar ran distraction). God thing Jozan can resurrect! (we're giving our cleric a work out here!)
10) AAAH! WITCH!
Baleful Polymorph has transformed them into sides of bacon, which, while delicious, are hardly fit to bring back. Odysseus comes to the fore again, his clever character and his obscene ranks in Diplomacy (combined with Charisma boosting items and diplomatic gear yoinked from Paris's vanity stash back in Troy). At least *someone* didn't treat it as a dump stat! Regdar gets eaten, and Jozan can't bring him back from that...(Loss+++!). Regdar's player whips up a new guy, a member of the crew who has proved himself time and time again, and who is being swiftly promoted in the ranks. And maybe when they get back to town, Jozan can use his pull to get him braught back to life....but maybe they'll be irked at him for pissing off Possiedon, too (danger+!)
11) AAAAH! HARPIES! Since Odysseus & co. still want to hear the harpy song, they put silence over the ship, except for the mast, where they strap themselves (humor, heroism ++!)
12) AAAH! WHIRLPOOLS! Scylla and Charybdis, easily Terrasque-level challenges, make short work of the rest of the crew & boats, and heavily damage the PC party. If only they would've made that DC 35 Profession (sailor) check! But even Odysseus couldn't save our land-locked PC's from their doom this time....the mooks..........are dead (Loss+++++!)
13) Home? The PC's make it to a friendly island, and tell their story (Perform checks all around....Odysseus, you saved them again! You even got them to send back tribute!). Then they're sent on their way...and a rumor (Krwyn's Gather Info check) says that maybe they can scry on Odysseus's kid....
14) Mialee gives it a whirl, but she's not very familiar with him....it takes a few tries, but fortunately, Possiedon isn't throwing any advanced Dragon Turtles their way, and she eventually does it.....and the kid is living in a swineherd's place....WTFBBQ? (Mystery+! Suspense+!)
15) They get home, and talk with Telemachus, find out the mooks are doing some damage in the home...a shame the PC's were only about level 10 when they left, just beginning to get their home and hideaway.....but if they just charge in, Od's wife is in danger of being massacred...even if they aren't....so, sneaky it is! And fortunately, Athena's Gifts (powerful magic items of disguise, also treasure for getting to LV 17) help them do it! Though the other three can ape their way through being old and poor wihtout jingling their magic too much, the world's only Charisma-Monkey wins yet again, with his magnificent Bluffs, Disguises, and Diplomacies....even against the Head Suitor, who is an of-CR challenge (one of zeus's bastards, after all...). In the aftermath of his drawing his Composite Longbow +2 that he got back in the day, but didn't bring to war for fear that the Trojan Monks would sunder it (and besides, he could probably find a better one in Paris's hoarde, or be given one by Agamemnon, that ol' codger...)....even though Mialee could mend it after that, it's magic wouldn't be restored, and it'd still have that little scratch that is quite unbefitting an heirloom.
There ya go, a classic tale of myth, adventure, and loss, in no way ruined by magic. Admittedly, it was a bit rail-roady (some DM's would've let them get home quick, and done Possiedon's punishment perhaps in the form of an earthquake-style campaign where they were forced to move the city itself, rather than the warriors from Troy), but I was following a rather strict campaign outline, and, admittedly, railroading was kind of the point (you can't fight the DM any more than you can fight the gods!).
The magic gives it a certain feel, it does NOT ruin the drama, especially when you don't assume the PC's are the only ones with it (verisilitude again)