Just because you are the author (or in a rpg, a co-author) it doesn't mean that the best thing for the story is for your character to do everything right, with no justification. Quite the contrary.
However, with no costing mechanism, you basically end up with your character's abilities being limited to what you, the player, can talk the DM into letting you get away with.
It is one thing to say that you can weave tapestries or repair mundane armor in your spare time and quite another to claim masterpiece-level-status in all trades and secret knowledge of each and every plane of existence.
In short, "If I don't think it will ever actually matter, do what you want; if it might matter, we need rules."
Or, in other words:
"Background doesn't matter; make some




up."
I knew I would have....issues...with 4e when the initial press conference on in, back at GenCon '07, had one of the developers (forget which one, sorry) saying, "If you want to know how to sew, just write it on your character sheet. It's not relevant to the game."
In short, in my games, you are allowed to shape your character in any way or form that fits the overall story. And by "overall story" I mean the consensus created between everybody at the table.
Within very broad limits, such as "We're running a swashbuckling campaign set in a high fantasy version of 16th century France, make appropriate characters", I agree. I might even go so far as to say "So far, the group is really missing a healer type...does anyone want to change their concept to fit that?" But I find the idea of "collective" character creation to be....communistic. I also have issues with "consensus storytelling" -- some of the best moments in RPGs come when two characters have wildly conflicting goals or the same goals and wildly different approaches to achieving them.
I see nothing in the 4E rules that prevents a character from being a smooth-talking rake, more at home in the political arena of a prince's court than in a grimy dungeon:
Then you need to look at the rules again; it is virtually impossible NOT to be at home in a grimy dungeon, and, for that matter, not to be at home in the political arena. +1/2 level to all skills and relatively low DCs (as per the errata) means that while Thrug The Barbarian^h^h^h Ranger With Pretensions might not be AS GOOD as Sneaky McLiesalot in social situations, odds are, he'll succeed pretty regularly -- a lot more than he would in 3x, at any rate. And even someone who pours every option they have into social skills will still only lose a hair of combat effectiveness, overall. This is by design: Everyone should be able to participate in everything, and character individuation be damned.
If you want, you can also reflavor some (or all) of your attacks to fit your concept.
And this is sort of the real key. The answer to so many complaints about 4e seems to come down to:"Change the fluff text." I don't find "reskinning" to be a satisfying answer to missing or incomplete mechanics, sorry. (If the 4e books used the same typeface and page count as the 3e books did, it would be an almost immeasurably better game, but that's a rant for another thread.)
The disconnect between the hyped "Skill Challenge" system and the rest of the mechanics is painful; it looks stapled on. At-Will/Encounter/Daily powers do not integrate well with a highly abstract system where a single roll might represent a second, a minute, an hour, or a day -- even within a single challenge, each "round" could be a highly variable amount of time. Where are the spells/prayers/exploits/feats which tie into SCs directly?
Again, no need to argue with the DM.
Anything that represents a conflict (be it a crossbow shot or a seduction attempt), must be backed by rules, even if in most cases its only something whipped out of the page 42 table.
Anything that's just flavor doesn't need backing at all.
Bingo. The assumption you (and the 4e rules) makes is "Anything which doesn't directly relate to orcs slain per hour is just flavor." The reality of gaming, though, is that you NEVER KNOW what will and will not become relevant in play. The idea that encounters have a fixed purpose and a fixed resolution mechanism for that purpose seems to be one of the developer's key pillars of 4e design, but in Actual Play TM, it's not like that. A recent Dragon article had a fairly cool idea about bugbear mafioso (in our current game, the mafia is run by the ogre mages, so there you go.) Anyway, a particular character, an ancient matron, was given nothing but three skill values, on the grounds that "the players won't be fighting her". Well, goodie. So she has one hit point and dies instantly in combat. Fine. Does that mean she needs no stats? What if someone uses a mind affecting spell on her? Or wants to sneak up on her -- does she spot him? Now, 4e DOES allow almost any check to be easily calculated if you know two things -- raw attribute and level -- but the article didn't see fit to provide even six stats and a level number for her. Why? Because the designers had decided she could not be interacted with except in a set, narrow, way -- and if the players crawled out of the box, the DM was expected to shove them right back in. (And if your answer is "Well, make up some numbers that seem right!", then, one could just as easily have written the article in five words:"Bugbear gangsters. Pretty cool, huh?")[1]
4e, the game system, doesn't force this. It DOES provide the tools you need to do what you have to do, even if the tools are much simpler than those 3e provided. However, there is a strong attitude, implicit and explicit, on the part of the current development team that anything not directly related to hitting things with sticks is secondary, both in terms of mechanical support and in terms of how much table time should be dedicated to it, and even though I am definitely coming to appreciate some of 4e's mechanical features, I find that attitude, which sprawls through the rules like some sort of...sprawly thing...to be very off-putting.
I am constantly surprised by how my players react to the situations I put in front of them. I have tried saving time by only statting out what I think I will "need" for a given encounter/scenario. I have found, though, that players will fight with the people you think they'll talk to and talk to the people you think they'll fight with -- not to mention avoiding huge swathes of plot altogether. I never know what an NPC will be called on to do, so the idea of deciding a "role" for an NPC and having all of their stats based around that role is, to me, risky.
Getting back to the main topic, though -- the same applies to PCs. I never know what background is "Flavor text" and what is going to matter for the plot. I also enjoy mechanics as an end in themselves. Even something as simple as "Here's a list of common trades and professions, with their most common associated attribute. Pick two. You get +2 in checks relating to each of them to reflect your pre-adventuring experience. Alternatively, you may add +2 to a single skill if that better models your childhood and adolescence." would do a lot to send the message that "Background matters."
[1]Also, we have a kobold with precognition. Cool! Except...there's not one word in the article about exactly what his powers are, their limits, anything beyond the note that he has such abilities. Great. So does he get a vague hint about the future every now and then, or does he greet attackers with "Hmmm, you're 2.5 seconds early. I'm slipping."?