It was just never clear what MS wanted to do with this, the reveal showed the game being controlled with Kinect https://www.youtube.com/watch?v=m37sVEgJrOA
and then they ditched it, brought Conker in a terrible way angering just about everybody.
The art style was all over the place, it just didn't have a great art direction like LBP, something u can pinpoint to and say "yeah thats that game", Project Spark felt like a reactionary move to the play.create.share genre boom. Just like many of MS' endeavors unfortunately. It wasn't a passion project. Ori and Cuphead, those are passion projects.