That said, I tend to fall into the "don't forget the roll" category, myself. If I find that points in diplomacy, bluff, sense motive, and gather info have absolutely no effect in a given game, I will not bother to put points there, plain and simple.
Shaman, if you told me up-front that my 10 ranks in Bluff wouldn't do me any good in-game, I'd ask to rearrange stats or just change the character, because I don't want to be at a handicap with the other player in the group with the 5 charisma who traded literacy for another +1 to hit, to borrow from Bront's famous comic strip.

If I see a 5 CHA guy being awarded the same respect and reverence as my "social combat monster," then it's as unfair as if he were casting spells with the same ability as the sorcerer in the group.
On the other hand, if the abilities WILL make a difference, even if I can't pretend to seduce someone to save my life and there will be a penalty for this, then I'm cool with it, and full speed ahead! Just as long as where I spend my attention isn't wasted.
EDIT: Looking back, I focused on:
The Shaman said:
The problem that I have with this way of thinking is that it takes my ability to roleplay interesting characters with complex motivations out of my hands as the GM, and makes the responses everyone in the world that's not a PC subject to the results of a die roll. That really removes any reason for me to create NPCs with any depth or breadth - they become nothing more than "targets" for characters with high ranks in the social skills to knock down, rather than contributing to the veracity and verisimilitude of the game-world.
Can't there be a happy medium, however? In my campaigns, 90% of the NPCs can be swayed with good enough diplomacy or a good poker-face, same as the real world. The remaining 10% can't even be persuaded with a DC 100 check - they're resolved to their actions, and no one will change their view. Even a stellar hasty (-10 to check) Diplomacy check will only make them sympathize with the PCs rather than change their mind.
My recent Eberron game featured a nihilistic Psionic Warforged who planned to end the world - even the best Diplomacy roll only meant one thing - he spoke with the characters before enbarking on his plan to destroy it all. He felt sorry for them, explained why he had to do it, and continued on his merry way - he was, after all, being helpful, and "risking" his plan by stopping to talk and let them know there was no hard feelings. No amount of diplomatic "you don't NEED to do this" would have helped; he was tired, and that was that. There's plenty of room for unique NPCs, and plenty of room for Joe Merchant, who with a bit of die luck and a good word from the player can cut them an extra deal, or warn them that he heard a rumor of a threat to them.