Is the GUI wallet eventually going to have a cold wallet/offline signing feature if it doesn't already?
Not yet. We try not to implement advanced/rare-used features in first few versions. If someone really wants to use them, I think, he can easily start command-line wallet for now
It is an advanced feature but I don't think that it is rarely used. In fact, it is a must for cryptocurrencies. If you implement it, users will used it to secure their tokens. Don't wait until people start losing their coins. Wallets for the top coins have such a feature. It should be standard.
Thanks for advice. It's not too hard to implement, we'll need another tab on UI for advanced features, I think.