Blizzard had this to say about the fact that the Blood Elves will not be getting warriors as every other class has so far.

We're not disagreeing with the statement that Blood Elves would make good Warriors. The fact is, many classes made sense for the Blood Elves. We wanted to choose six, however, to keep the number of options in line with the Draenei.

The fact of the matter is we're quite pleased with the six classes chosen for both of the new races and we don't feel that we're breaking the game by breaking the tradition to allow warriors as a class option.