You can't be fine with something of which you don't know how it works exactly, I wish that was how it worked but it doesn't. They have their own variation that takes into account these things but they don't just want to post their system, which is really weird since Elo is a really simple system and there are tons of Elo based ratings out already so I don't see why they can't just throw out their algorithm.
They use a modified version of Glicko (created as an improved version of ELO), which works pretty fine... if you can overlook the pretty big problem of having only one rating per account, not considering teams/solo queues/characters or anything.
Again, modified. There's no reason to modify Glicko/Elo in such a way that you wouldn't want to publish this... I really don't get why they don't just throw their algorithm out there. Both glicko and elo are known as being reliable.
And as you said yourself, the things which should be modified (don't really have a lot to do with MMR) should be looked at/improved instead of fidling with the basic Elo system.
P.S.: (isn't glicko elo but with rating decay?)
The majority of Guild Wars fans and players were European historically. Directly from Arena.net at Pax.
Wouldn't surprise me if that was true of the sequel as well.
Hmm, not sure if that's the case.
NA's 24 servers
22 are Very High
2 are High
EU's 27 servers
10 are Very High
3 are High
14 are Medium
Unless there is enough population on EU's 3 extra servers to tip 12 Medium servers over to Very High it would seem that the US region currently has more players. Hard to tell.
Talking about the sequel of course.