Well, the title pretty much says it all. We're basically getting 6 new races this expansion, with more coming down the line if everything works out as Blizzard plans, and i imagine that a lot of people would like to roll some of these new races, without deleting some of their older chars.
I always thought that the slot cap per server was a bit unnecessary, but i really think that in light of these coming developments, it's time to uncap character slots per server. Keep the 50 max per account, but let me make all of these 50 characters on the same server if i so choose.
I'd be interested to hear from people with more experience and insight into server technology and limitations if there would be any technical problems with implementing this. I always thought that it was more of a business decision, with server transfers costing money and all that, but with servers basically becoming an irrelevant thing with the new pvp/pve toggle, i guess that wouldn't be much of an argument anymore.