Yumia didn't have the same twitter trends to attract all the tourist coomers that Ryza did. Her game also was a bad atelier title even though it was a pretty impressive rpg coming from gust. The atelier fanbase simply isn't big enough to recreate another Ryza. Tourists came for Ryza and left after it was over. It's a similar trend with Kiseki and cold steel. People came for Rean and left when his arc was over.