I would agree with those who have stated that heroism is possible in D&D, but I would also maintain that D&D, as published, is not an optimal system for high heroics.
Bravo! My sentiments exactly.
Dragons have to be sneaky because DMs balance encounters to their PCs. This makes for an even match, and then tactics are extremely important.
If you want dragons that can burn and slay without thinking, just use a dragon 8-10 CRs above your party level. It'll never have to get tricky, just swoop in, Power Attack at +50 damage, pulverize that poor fighter, and continue its Flyby Attack. Repeat as needed.
But it shouldn't have to be that way. Or rather, it shouldn't have to be a zero-sum choice between tactico supremo and plain ungodly a**kicking. In an epic (figuratively) or heroic game, the final battle should last longer than few seconds without unbalancing the encounter. An EL 12 party should be able to fight a CR14 dragon toe-to-toe without having to resort to cowardly tricks. In other words, the party and the dragon slug it for rounds until one side loses or flees (successfully, I might add).
Current rules aren't optimal for the above scenerio, though. One Harm, the dragon could be a toast. A Ftr12 would be dead in couple rounds unless the fight ended earlier. If you believe that you should make the optimal uses of rules available, as many people do--as evidenced in the popularity of threads about smackdowns and min/maxings--about this topic, then combat between the evenly matched become necessarily quick and decisive. Unless there were some horrendous/lucky die rolls, of course. My pcs, EL10 now, will take out most CR10 opponents in one round+partial action. With surprise and initiative, few opponents of their CR will even have a chance to draw their weapons.
A d20 game that kept fast paced, heroic gameplay in mind, where foolish heroism is rewarded, would be cool. And I think it's do-able.
Doable, yes, but somewhat self-defeating. I have, on occassion, done things that have kept things more heroic. DR has proven admirable in forcing the combat to last longer and more grueling; a bump in DR has negated the advantages of surprise and initiative without overly powering up the baddie. So has blindsight, both SQ and the spell. None of these, though, can be used often without becoming cliches, i.e., "oh no, another DR, screw my boots of elvenkind, I'm getting me some boots of striding and jumping!" As for the spell Blindsight, bah, a standard tactical doctrine with my pcs is for the shu to cast dispel magic as his first action...
I would say most DMs don't hink ahead when they put their bad guys in situations against the party. A smart bad guy is going to monitor the situation at hand. If a fight breaks out he is going to weight the rsisk versus the rewards. If there is too much risk, he needs to take off and the DM needs to make sure he has a logical (by the rules) way of escaping
I have nothing against having smart villains; what I don't like is the excessive emphasis in the Rainbow Six type action to be successful in the game. I think there's a happy medium between foolhardy charging into the unknown and sending in animated animal skeleton with echo skull spell atop it to scout ahead, the party staying apart 30' each to minimize area spells while still able to come to aid, the rogue going ahead and checking every darn brick for traps and using hand signals to alert the party of any developments, always hiding while moving (taking hits in movement), invisibility to animals on constantly to foil animal spies, pass without trace, sweeping areas constantly with detect magic, ad nauseum.
I've always longed for a more Rainbow Sixish campaign. A campaign where more than one character knows how to move silently and climb walls.
Let's swap players.

My pcs would make the Rangers and Seals very proud.
P.S. I don't mind my players' style of play, as I knew that would be what I'd be getting when I started dming. I may be a dm but I'm not a tyrant like many other dms are; I'm more like the British prime minister--I dm because I have the consent of the others. Before we started, we laid out a ground rule to have as mechanically canon game as possible. What my pcs are doing make perfect sense; in fact, I've been guilty of breaking our rule by surreptously burmping up the DR a few times.
The game play within my game has been, quite frankly, fostered and encouraged by the current rules. I've made the optimum use of the rules, and so have they. Nothing to begrudge on either side.
It's just unheroic.