pirates first and foremost reason is not being willing to spend money to play games. why spend 80 euros/dollars/counterparts in pounds or pesos or whatever, when you just need a 20 euro/month internet connection with high speed to download anything?
... (considering buying them when they do come out, and not after six/seven months) around the 60 to 80 euros (i'm considering italian videogames prices nowadays) ...
now immagine a "good year" (like this one) how many "good" (hyped) games came out? twelve? fourteen? let's go with the average.
13*70=130*7=910 euros+obviously the monthly internet fee of 20 euros, so it's 20*12 240+910=1150 euros of yearly cost in games.
as a "pirate" you would only have payed the internet connection, or in case of a free wifi zone, not even that.
You don't HAVE to buy everything when it comes out. That's just a way to make sure that you spend the most possible on every game that comes out. So, instead, you watch sales, particularly Steam sales, since 75% off sales come up quite often on Steam, and their summer and winter sales are amazing. There may be a few games you want to get immediately, but you may make an exception for them and find a way to get them cheaper (Trade in old games, for instance).
I've bought at least half a dozen great games this year that I hadn't played yet, for $5 each on Steam, and a few others for more. I didn't even get Deus Ex: Human Revolution full price since I got the discount from pre-ordering it on Steam 2 days before it was released, and I bought Portal 2 while it was on sale in Best Buy a month or two after release.
You mentioned that you pirated V:TM:Bloodlines. I bought it on Steam for about $5. With Steam's auto-patcher disabled, I installed the unofficial patch and such and used the resolution patch and had it working just great.
world of warcraft has free shards around, but not guildwars. Why is it?
hackers/crackers won't touch a drm.free game with no security. because it's NOT a "challenge to their skills", people will buy it and play it, and keep it because new contents will be freely added as long as the game keeps being bought, by maybe people who heard of how good it is.
You know guild wars has no monthly fee, and world of warcraft does, right? I should think it would be obvious why there are emulators for world of warcraft - people don't want to pay. Of course, there's also the "I want control of my own game world, to run my own for my friends," but there have been many other more mature avenues for that for years now.