I think the whole "roll or role play" for social interaction thing is entirely a matter of personal preference.
Here's mine.
To me, I think that "the player is not the character" is a fair argument. I also think that players should be rewarded for their ingenuity and role-playing.
So what to do? Well, the obvious answer is to
wake up to the fact that it's not a freakin' dichotomy!
Have you ever heard the turn of a phrase that goes "He could sell ice to an Eskimo"? Obviously, that statement refers to someone who is very good at convincing others. Such a character would have a high diplomacy (or bluff or possibly profession: merchant, depending on how you handle it.) But it's pretty aparrent to me that selling ice to an Eskimo is not a particularly clever sales venture to begin with, so it would have a high DC.
Now this principle applies to interaction skills in general AFAIAC. It's up to the player to describe what they are doing, and the dice decide how well they do it.
I don't think this is unreasonable at all. Gamers being a oft times socially awkward bunch, I am sure you can relate to me here.

How many times have you had an out with a friend or girlfriend and thought up the PERFECT thing to say to mend things over, then when the conversation actually came, things went south, didn't come out as you intended, etc.?
Well, that's just a representation of the dice in motion AFAIAC. The GM can evaluate whether a player's approach is inherently appealing to a target, and set the DC appropriately. Then the dice determine the delivery. A bad roll might mean that you came off as arrogant, inadvertantly committed some faux pas, etc. A good roll might mean that you caught them in a good mood, reminded them of something, impressed them by sticking with your guns.
I have seen some very good guidelines in some d20 books (I don't know if all these have migrated back to the PHB right off the top of my head.) For example, I seem to remember in CoC d20 that they had bluff guidelines like "target wants to beleive" and remember a diplomacy guideline like "PCs request puts character at risk." That sort of thing.