The problem with starting subscription based and then potentially going B2P or F2P is that the game is 'designed' as a subscription MMOG, IE it is designed to have content that takes forever to participate in, designed to have a grind to keep players logged in for as long as possible, designed so that people will be forced to go through a bunch of hoops just to do anything because time = money.
The great thing about GW2 IMHO is that it was designed from the ground up to be a B2P game, so it does away with a huge amount of that kind of crap. You can get anywhere in the game world in an instant. Dungeons don't take two hours to set up and four hours to play through. Simple things like transfering crafting mats to the bank because they don't need to force you to run to town when your bags get full (time=money in a P2P) and more.