I'd love to do priv key import, but it cost isn't worth the usage. We won't ever import a foreign key into our wallets which means we'd have to set up a duplicate wallet for every coin. It just isn't viable. If you have an idea of how to accomplish it, i'm all ears.
As for forked coins, @blocktalk is absolutely correct. We either upgrade and follow the majority fork or risk being on a broken unsupported chain. It isn't about us supporting devs; its about us supporting the majority of users of any given blockchain.
RE: Hi, my name is Richie - I am one of the founders of bittrex.com