Most of the revenue the game makes via subscription doesn't go back into the game, but to Square Enix, who use it for other stuff. So their content is still on a budget.

Anyway, I am fairly certain the new hairstyles for female Viera will come out at least with patch 6.0 or 6.1. Everybody currently playing the game (whether or not they own EW) will probably get access to that when the game goes live again. Again, whether or not male Viera are restricted to those who own the EW expansion or not is unknown.