One of several criticisms that I've seen about Dungeons & Dragons is that the use of social skills removes role-playing from the game, which has always confused me because role-playing is more than just talking to NPCs or character-acting: at any point in time that you assume the role of someone or something else, you are role-playing. If I am running around killing harpies and undead legions in God of War II, I'm technically role-playing to some degree.
However I've come to terms that when most people mention role-playing, they are emphasizing character interaction over anything else, if they even consider the other elements to be role-playing at all. I think a more focused term for that is social role-playing, and while some think that using skills and dice to determine the outcome is bad, I think that it adds consistency and immersive play since the mechanics of a character are supposed to reflect what she is good and bad at.
My preferred method of utilizing social skills, such as Bluff and Diplomacy, is to have the player roll first and then interact based on the results of the roll. This is because I prefer the actions of the character to succeed or fail based on the merits of the character, but also because it makes things fair for all the players regardless of their personal talents and skills. If your character is stupid, don't expect to do a lot of intelligent things. Conversely, just because you are socially inept does not mean that you cannot play a character with a high Charisma.
If I allow the player to come up with a really good plan, then it feels like I'm short-changing them when they roll and the plan fails. I used to give out bonuses in those situations, but I felt that it was a pretty one-sided benefit that could end up "breaking" character depending on the character, player, and suggestion. Also, it only favored mental and social skills, not physical ones like Acrobatics or Endurance.
I don't think this method penalizes players who are really intelligent or silver-tongued, as if they want to play a character that is smart or great at talking, they are more than free to. Heck, D&D makes it pretty easy to break the mold with Multiclass and Skill Training feats: I played a barbarian that I wanted to be an excellent leader, so took Student of Battle and picked up Diplomacy. One feat and I got some great benefits out of it that reflected the character's personality and experience.
Anyway, I'm not about to penalize a strong character that is being played by a physically weak player. I'm likewise not about to give a player a bonus to Athletics because they describe a really good way to lift something.