While Blizzard may want money they still want to prevent some dumb things from happening. They don't want people just changing races to the current FotM race such as every horde shaman going orc in 3.2. By making limits they are making it more of a cosmetic change (as it should be) rather than having people just change based on racials.
There's still going to be plenty of people that use this service for the explicit purpose of getting new racials. The difference is that those people are going to affect the faction and/or server balance (if they are forced to move on a PvP server) every single time instead of only part of the time, because some of those folks may have just switched races within their current faction.
If anything, the fact that they are planning the entire development of a feature around this just seems like an open admission that they don't intend for racials to really be balanced at all (unless the deployment of this feature coincides with the removal of racials altogether, which isn't very likely). We're still going to see an increase of UD Rogues, they're just going to be ex-Gnomes or ex-Night Elves instead of ex-Trolls. It's completely arbitrary and points to a very large design failure that they have to make such large considerations in the first place.