If this new standalone photo app will let me easily, quickly, flawlessly upload photos to Facebook, then hell yeah.
It is hard to optimize for different tasks at once, while I'd also argue it would be possible to strike a good balance. But I think it is a pragmatic decision rather than try to achieve that perfect balance, and let several instagrams take over, do the right thing for each task and a year down the line knowing usage patterns, with much better hardware, you can think about a consolidated app.
I think they should fix it. But if their current solution is to make the photo taking/sharing a separate app, that's fine with me. I use Facebook mobile more to take/share photos than anything else on Facebook.
Ultimately I think it boils down to what you think of when you want to do take a photo or send a message which maps to (Facebook Camera, Facebook Messenger) more naturally than just Facebook.