I have a feeling they know the number of people being denied log in and realize that a second server will likely not eliminate the problem. The real problem is the server cap - having a server cap only incentives people keeping their AFK characters logged in. If they added the number of servers necessary to serve this initial rush, they probably fear having a bunch of ghost town servers in 2 months.
Unfortunately I think this is only a precursor to more serious issues, like having enough high end content to support ~50 people and having a server that will likely see everyone bolt for the level cap. They need to really rethink their stance on instancing or open up a lot more servers. I think this server is going to require instanced versions of Guk and Sol B, and likely the planes as well.