Tentatively:

If it's accepted that GREEN* and RED are structurally identical, and that in virtue of this they are phenomenologically identical, why think that phenomenology involves anything, beyond structure, which needs explaining?

I think this is the gist of Dennett's dissolution attempts. Once you've explained why your brain is in a seeing-red brain-state, why this causes a believing-that-there-is-red mental representation, onto a meta-reflection-about-believing-there-is-red functional process, etc., why think there's anything else?