We had DirectInput for years before... the only reason xinput has become so common is that most games already support it (because they have a 360 version). I personally hate xinput... doesn't let you use any USB controller, most games that use it don't let you assign functions yourself. When games used DI the games (that supported controllers) let you assign things freely and worked with any controller that was detected by Windows.

Wait... you said controllers are bad for FPS games? (I agree 100%)

But an hour later you say not using a controller in an FPS is difficult?

Am I misreading something here?

Yes and no. The problem is that when they design the game to take a controller, they make adjustments necessary to make it work. The problem is that you can't undo it just by plugging in a mouse, a lot of the games mechanics are adjusted to make use of the less accurate controller.

Hence the seemingly contradictory position. In general it's better to use a mouse + keyboard, but when the mechanics have been adjusted for a controller, you sometimes end up in the position from time to time where the game plays even less well than with the controller

Then you've got games like the latter FO games, where it's an FPS at times that uses a controller, with RPG action on top of that making for a miserable experience when trying to use mouse+keyboard.

actually no they're not, until MS standardised their allowed inputs controllers were not plug and play they almost always needed a driver download and those that didn't generally had misnumbering of the buttons and vertices.
USB HID's have only 2 other standards which cover USB keyboard and USB mouse the mouse one only covering 3 buttons and a scroll wheel for example they are not plug and play beyond basic functions. There are a number of informal standards but don't mistake them for PnP

Unless the best method is a joystick or steering wheel :)

USB HID is a formal standard that defines a lot more than just keyboard and mouse.

Are you talking about automatically mapping the controller inputs to game functions? Because being able to change those is quite important for many people. Such as a friend of mine who has no feeling in her left hand.

Xinput annoys me a lot since games using it often don't bother to support HID devices like my joystick and my friends steering wheel in games where they're the best controller (we've gone through over a dozen games in the last few days that did that)

Obviously, flight sims (not exactly overly represented these days) and racing sims usually works best with a flight stick or racing wheel, in that order. But you should be pretty well covered if you have an X360 controller (for modern games), or one of those nifty ones I consider getting from Logitech, where there's an Xinput and "old standard" (can't remember what it was called) switch for better support in older games. But nowadays, X360 pads are great for modern gaming on PC. It's a shame about bad/lazy ports, but that's reality, and while it happens more than before it's because there are more ports than before (because the PC isn't the lead platform for developers anymore). There are games that doesn't have ports at all that I would love to play on PC and would hugely benefit from it (like Red Dead Redemption and L.A. Noire - what happened to you Rockstar, you used to be PCD friendly!).

I wouldn't say they were ever really PC friendly. While the PC was an established platform it simply made sense for them to make ports and TBH none of their games were especially well ported, just look at the shockingly bad joypad support in GTAIII, Vice City and San Andreas. Rockstar started out as Amiga developers then moved to consoles, hell GTA was originally to be a Saturn and N64 title. I think Rockstar just no longer see the value in porting their games to the PC lazily anymore, it's simply not the quick cash in it once was.

x360ce can make your controllers show up as Xbox 360 controllers, complete with analogue sensitivity and even rumble (if your controller supports it).

An alternate approach if you have problems with x360ce is to use Xpadder or the like to send mouse and keyboard commands through your controller; unfortunately doing it this way means you will only have analogue sensitivity for the axes bound to the mouse and the game won't send rumble to your controller.

EDIT: note that while rumble works no workaround will get actual force feedback working even if your controller supports it. The official 360 wheel's force feedback isn't supported on Windows so no workaround can do this either (at least as far as I know). If the game doesn't natively support specific wheels in addition to 360 controllers you're out of luck. :(

I guess you're kinda right. The only problem I have with joypad support in the GTA 3 series is that my right analogue sticks seem to be messed up (up is left, right is down and so forth),

But GTAIV works well with an X360 controller though, so it's a decent port outside of the optimization. But sheer power will work that out (over time), and the game already looks much better and runs much smoother than my X360 version ever did.

PC is still an established platform though, and probably more popular than it was 10 years ago, thanks to digital distribution.

no all USB HID covers is the system calls to define a settting of keyboard, mouse, controller or other. and the ability to set a protocol, descripter, idle command or a report
everything else is covered by specific drivers. USB HID is not some amazing thing it's just a connection protocol.

As for not allowing control scheme changes blame that on the really crappy workloads you get in game programming.