Crap work from the studios is the reason games are not bought.
Take for example Football Manager (previously called Championship Manager and probably the greatest game of all time - objective view here). The Collyer brothers removed SecuROM from their game with their 97/98 version (or was it LaserLOK - meh, just got softcapped) intentionally to spread the word about their game (Hey, my first experience with their footy sims came from a pirated copy of CM 97/98). They sell out crazy every time they release a new game for one reason only - they keep upping their standard for the game. Every year sees improvements to the game that many fans find brilliant. If they rested on their laurels and did bugger all to improve the FM experience year on year - they would be pirated to kingdom come and back. OR they would be clever enough to just do roster/regulation updates for a minimal cost (eg: R100).
On the other side of the coin is Fifa (disregard the last two iterations where EA actually tried to improve the mechanics of the game). I never ever bought a legal copy of Fifa after 99. Never downloaded a demo - only the full game and after trying it out for a while I would delete it (then again, after Fifa 2000 I started playing PES and said to hell with Fifa, and PES was a pirated copy because I couldnt find pes anywhere to be bought legally).
To whit - the only games I buy (regularly)(except for last years editions) are Pro Evolution Soccer (it gets better with every year, barring the 2008 edition) and Football Manager (this game really does get better every year, nuff sed).
I've bought NWN when it reached a good price, I'll be going to buy Battlefield 2 and CoD4 for R100 a piece once I get my new PC (what would the point be of getting illegit copies of multiplayer games - seriously).
Piracy is not killing the PC, a bloody boring rehash of games is. Halo 1 & GTA 4 broke sales records because they were innovative and fun and made you want to play games again - not because piracy was a setback.
@the moron who said that GTA will not sell a million copies on the pc. Rubbish. It probably won't sell as well as on the consoles, but then again most people who play game son the pc have a console as well and those people already have GTA - otherwise, anyone who doesnt have GTA on the pc will buy it rather than pitrate it - just because of the multiplayer component. nuff sed