There's a big difference between Guild Wars and Battle.net and a real MMO. When you need a server for say, 2-12 people, just about anything could do. Halo, for example, simply utilizes one of the player's Xbox as a server. Once you go beyond that number things start getting costly. 32-64+ player shooters need dedicated servers to run smoothly, and if the developers are unwilling to foot the bill then players have to.

Now up that to over a 1000 people and you need some seriously powerful hardware, plus a team of technicians to run them all, and I imagine some costly internet bills. You need some type of subscription of RMT model to pay for it all.

Now if Guild Wars 2 really is a persistent world MMO (re: not composed 99% of instances), and it really is free (no RMT or sub) then I will believe you.