User blog comment:Furi3210123/Sonic Runner's Data Leaked/@comment-1392727-20150228143134/@comment-4533965-20150228150759

Probably because she looked too "realistic" prior to the minor redesign. Plus, it honestly for better with the theme, like notice how Sonic looks like the current self but has aspects of his classic counterpart. I think they're aiming for a child-like art style.