Steem is a very distinct blockchain where there are posts and votes. There is value therefore in providing a way to work with these kinds of transactions as you did with chainbb.
On the other hand, a crypto-currency must have some local way to send funds and use the owner and active keys. The idea of putting private keys into a website like we do makes my stomach turn. That is why Vessel is an important project. Of course being a witness should be your core concern. Are you going to keep maintaining Vessel?
I'm planning on releasing a new wallet to replace Vessel with. In the short term, yeah I'll make sure Vessel is still working, but long term it'll eventually it'll be discontinued too.
One of the things I'd like to do is make an easy export from Vessel and into this new wallet process. Try to make the upgrade easy.
Why not join forces with me and make a gui front end for steemboat. I will put it up on github. It uses python so it runs on 32 or 64 bit. It should work on Windows too!