>>149067558 (OP)I'm not sure if I have any confirmed sources from the staff but the commonly spread word is that the first season's production was a mess with a lot of the staff being new to animated televison. Ten percent of the original order never saw the light of day, believed by many to be due to the budget going over, and the second season saw a major change in how scripts were done (going from board-driven to script driven) and the studios that handled the animation itself.
Ben himself in 2012 officially said that they had to adapt the season 1 art style to more complex animations.