After about a year (or is it two) they did fix a lot of the issues with GTA IV as they released the update for the DLC package (episodes from liberty city), removing the need for the standalone Social Club application, and the need for signing up for said social club to even save your game.
It's still rather more cumbersome to work with than it ought to be, but it at least runs ways better and has less big bugs.

That being said, I can understand why they're in no hurry to port the game to the PC. Last GTA style game they did on the PC which was well optimized and quite playable was Vice City. San Andreas was okay but was once again falling into the unoptimized slump thing. It was nifty with the mods able to be played on it though. And the mod which allowed increase view distance, so you could stand on top of something in Los Santos and see the buildings in Las Venturas and San Fierro was a very nice touch and also would not have been at all possible if there wasn't at least some sort of optimization in the engine.

Also, I'd say you aren't missing out that much on Red Dead Redemption. for me it plays mostly like a pretty screensaver with minigames and a couple of action sequences. The gameplay is much better lent to leaning back in the couch relaxing than it is to sit up and play in front of a computer.

Then again, I'm the kind of gamer who finds computer RPGs mainly boring because they contain a lot of talking and very little in the way of actual action.