Isn't this shitty game design? Shouldn't all your attributes be affecting combat abilities and influencing your style of fighting?

Counterpoint: DnD (and PF by extension) should be about more than combat. Sure, some groups run it as a tactics combat engine and leave it at that. But there's so much more you can do with it. There are other ways to gain XP and treasure than straight-up bashing skulls and taking treasure from dragon hoards. I can't count the number of sessions I've played where everyone was having a blast and still getting XP and treasure, and we had not a single fight.

Sure, a lot of it does depend on the DM. But that's true of any other tabletop as well. And yes, it does suck that there are not as many options for using social stats in combat. Charisma would be great for feinting, Wisdom for predicting enemy attacks, and Intelligence for calculating weak points in an enemy's defense. But boiling combat down into simple terms: How hard you hit, whether you get hit back, and how bad it is when you do get hit back: those are the essentials of melee fighting.

And putting points into anything is never totally useless, just as useless as you make it. Sure, if it's a competition between a fighter and a bard for who can be the most charismatic, the bard will win regardless of how many points the fighter puts into Charisma. But you don't have to compete with the players around you. There's absolutely nothing wrong with saying "I want a suave, womanizing fighter," and putting a bunch of points into Charisma. True, you won't be as good at hitting things with your sword, but you'll be better at wooing the ladies with your club (if you catch my drift). Nothing is making you compare your character to anyone else's, that's a choice you make.

The game is quite simply what you and your fellow players make it.