I heard spirits are hard to do, but I'm wondering if they're isn't any tech to either simplyfy it or maybe go with cellshading.
There must be a happy medium where they can offer something more vibrant and drawn looking with the ease of development and ability to add costumes etc.
But I liked their one game one green approach this cycle.
Looked no further than what Arc System Works has done with Dragonball and Guilty Gear.
Moving away from sprites has to do with cost not difficulty. That is not just games, but all mediums (CGI cartoons have pretty much taken over for example. Once a model is made it can be reused for the entire run and can easily be updated. Sprites not so much.