It much depends on the kind of people who pirate.
If we take piracy in windows, then that's undoubtly what made it so popular as it is right now. So in that way you could say it's bad.
Some people go and buy all their games (spending all their money on that), and find that roughly 75% of the games they've bought they don't enjoy at all.
Then there are the other side with people who pirate most everything and use the pirated copies. Those guys do hurt the developers a bit since they don't pay for the stuff that's worth it.
I'm in a middle category. I don't have a problem with pirated software, and if I like the software then I usually go and buy it. Thus the developers who make software worth using are supported. Whereas the first group who buy everything will support all developers, even those who make crap but have a good marketing team. Take Dai katana for an example. Plenty of hype, but crap game.
Of course the price is a factor in how many people who will buy the originals. Steep prices mean that people will have to think better of wether the game/program is worth the price asked. I hadn't planned on buying duke nukem since it looked good, but I hadn't played it and I was somewhat sure that it would be a disappointment. When I found out that the suggested retail price was half of normal games and stumbled across it I bought it without much thought. And actually that's one of the better games I've bought. Most other games I've bought without having a demo or copy usually ended up disappointing me greatly.