Well, I think, that features can't be implemented in a few days and there's other higher priority tasks that are way more urgent than a little inconvenience when filtering characters.
Just wait, everybody likes the idea of having better filtering support, but it may take a while for it to become a thing.
Because it both isn't interesting for us (Trade drains coins from circulation, for one) and would be a hassle if we were to make it so exchanges were truly equivalent and not abused by players. You are already perfectly capable of selling characters and then buying whichever you want anyway, the "hassle" removed with exchanging is one step of that process.