i don't think anyone's suggesting that you support other altcoins. but being able to access the airdrop coins would be helpful in allowing us to sell them off in support of BTC, as another way to look at this. i for one, really appreciate being able to get at my BCH. i also look forward to doing this with BTG.
Your question was specifically about changes to BCH addresses. I do not want to pollute the GUI with that stuff. I don't mind adding a signer, but when the changes required to support the airdrop introduce complexities in the GUI, at that point the cost to support outweighs the benefit.
Bcash has been around since August. I think people had plenty of time to move their coins since. I consider I have fulfilled my responsibility to Armory users on that matter.