I greatly prefer mechanical support for roleplaying, or more generally, non-combat abilities. To me, any variant on "If you want to be the blacksmith's son, just write it down on the character sheet and get on with the game" is basically dismissing roleplaying as secondary, or utterly irrelevant, to "what matters".
Well, I obviously disagree, let me try to explain my point of view...
The "Well, the DM can just give you a bonus if it seems important" argument can lead to "Well, my character was the son of a blacksmith who was apprenticed to a wizard and was then kidnapped by orcs and was taught alchemy by a shaman before escaping to join the thieves guild until he was pressed into the militia where he became a master of arms and was also a quartermaster so he's good at economics and then he was trapped in the wilderness so he learned survival and pathfinding and then he..." I mean, why not? It's not "costing" you anything to have a background which includes any imaginable skill, right?
This is a common failure for aspiring writers, and its known in the fan-fiction world as the
Mary Sue/Marty Stu syndrome.
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.
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, 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.
If something is an important aspect of my character, I want it to have mechanical support. If I'm supposed to be a smooth talker, I want social skills, and if his gift of gab is more important to him than his swordsmanship, I want to the ability to reflect this by choosing improvements to his social skills over his combat ones.
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:
Start with a high-cha build (there are several options here, I won't elaborate)
Train Bluff and Diplomacy, and eventually pick skill focus for both.
Choose Cha when its time to improve your ability scores.
If you want, you can also reflavor some (or all) of your attacks to fit your concept.
Finally, choose a gaming group where the adventures will lead more towards investigation, intrigue, and social interaction, than outright combat.
Again, there is enough info in the DMG to run non-combat encounters and I am sure that any DM worth their salt can make enough non-combat challenges to suit any style.
I don't want to be stuck arguing with the DM over whether or not my rules-independant background flavor text does or does not matter in a given situation -- I want a skill/feat/power/option/whatever that says if it does, how much it does, and how often it does.
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.
Way back in the dawn of time, when I started playing MMORPGs, I would make up elaborate backstories for my characters. Eventually I stopped, because it sank in that there was no point to it, there was no mechanical support for anything but killing, and that you couldn't have goals for your character in the world because the world could not be meaningfully altered. You couldn't dream of assassinating a king or avenging yourself on the orcs, because there was no way to accomplish any goal not pre-programmed. So I just gave in and played like everyone else, questing for the phat l3wtz. I had, after all, P&P games for REAL roleplaying. If you strip the mechanical support for personality traits, goals, motivations, etc, out of a P&P game, though, you're playing an online game with crappy graphics and a server that needs a constant supply of pizza to keep running.
There is nothing in any edition of D&D that suggest pre-programmed goals. And although I grant you that some people play a "kick-in the door, kill the monsters, get phat l3wtz" style, it is certainly not my style, anymore than yours.
Best regards,
Amphimir Míriel, bard and minstrel