To me it seems like Open Whisper Systems are accepting a lot of concessions in order to have Signal included into products. The trust I once had for moxie is quickly dissipating. * Privacy is only provided in Allo in a secondary mode. Not by default. * Federation of the Signal protocol has been rejected for non-technical reasons. Also, on a personal note, the desktop client requiring chrome is pretty awful.
An incognito mode allows the default mode to have more functionality, and matches their approach with Chrome. It's not a bad tradeoff.