Rift and Lord of the Rings Online both have lots of players out in the world. While in WoW there are players out in the world, they had to create CRZ to have it happen. Consolidating servers (like Rift did) would have accomplished this as well, and probably taken less time. "But what about the names?" Easy fix: If 2+ characters have the same name, take the oldest one and let them keep it, and the others, change one of the vowels to have one of those stupid symbols over it.
Number of players =\= better game. Numbers only matter to a certain type of person. Enjoyment makes a better game. While yes, I will admit that at a point the number of players will affect enjoyment. But in the case of WoW, the playerbase is so excessively spread out that it feels like there is hardly anyone playing (especially on many realms). And this population disparity keeps feeding itself when people would rather play on high population servers. This was very apparent about a year ago when there were many threads here saying "Which shard has the highest population?" so they could continue to increase a single server's population while the others continueto feel empty because everyone was converging on a single realm (Wolfsbane US and Icewatch EU).