The FTB Unleashed limit has been set to 10 as the server is still under testing. Since the map has just been reset and Advanced Information Panels have been banned (due to them crashing the server), you could say the server is still in it's testing stage.
If the server remains stable since the AIP's have been removed and banned, I'm sure Broonie will consider increasing the player limit.
Until then, please be patient, as Broonie can't find and fix all the bugs within a few days. If you remember (and I remember correctly) - the old Tekkit server was run for a couple of months with only a select list of people being allowed to play on it (to track down bugs and fix them).
Put simply - Broonie knows what's best for the servers, and he will improve things as and when he can
