Perhaps a portion of those people pirated because there was no demo - the temptation has slipped (but never surfaced) when a game has no demo to pirate it in order to see if it'll work with my system spec. For example Far Cry 2 I almost did, because I wanted to buy it, yet there was no way to be sure that I'd encounter a poorly optimized console port or a well optimized game. But I didn't. I decided it wasn't worth it.
The numbers I'd probably put down to popularity and hype, not lack of demo.
But generally I don't like it when a PC version of a game is released and no demo is available. I mean, it doesn't even have to be a fully playable demo, a benchmark like the Street Fighter game and Final Fantasy XI had would suffice. Neither allowed you to play the game, but tested whether or not you could play it on your system. When it comes to knowing the gameplay, I just check out reviews, previews and watch YouTube videos of people playing when a demo is unavailable, as well as look up what problems people are having on the tech-side (if a PC game). There is a perfectly legal way of working around not having a demo.
