You know, back in the day, I would of been completely opposed to pirating games in any form. However, back in the day, developers and publishers put out demos constantly, to make you aware of how awesome their product MIGHT be. In this day and age, major publishers don't even bother with putting out demos, because they know that no matter how bad their game may be, if they market it right, they'll make a lot of money simply off of hype alone.
In the age where demos can be downloaded to our videogame consoles for free, I personally feel like there is no reason for a publisher to just put out a game, tell us to buy it, and expect us to without even giving it a try. I was very skeptical when Arkham Asylum put it's demo out, but after playing it, I felt like it was worth my money, which I cannot say holds true to a lot of games.
Due to this, I am 100% for pirating a game, if you honestly in good faith want to demo it out. I pirated my copy of Amnesia, but after getting about a half hour into it, and seeing how good it was, I immediately went to the developer's webpage, and bought the full game. Publishers and developers don't seem to give the users the luxury of being able to demo games like they used to, and with as tight as money is now a days, I'm not going to spend my hard earned cash, on something I'm unsure of. They need to make me want their game, not tell me that I need it.