Betrayed expectations. Everybody, including myself, had a mental image of something more similar to Shin Megami Tensei Nocturne. This (so far - again its becoming more clear we aren't seeing everything) looks different enough as to cause some tonal and expectations whiplash.
I think some of those expectations were misplaced. Personally I always thought it made more sense for the Devil Survivor team to be working on this, while "Team Maniax" worked on whatever next SMT project Atlus has planned in the vein of Raidou, Strange Journey, and SMT4. Either that, or this project was vaporware. Turns out it's real, and the Devil Survivor director is indeed the producer.
I mean just ask yourself, if you're Atlus, why would you prioritize your key development staff on an untested collaboration project which you won't fully own, rather than working on the next entry in a franchise which you have full control of and would solely profit from it.