Power forwards take longer to develop. Go look at Tom Wilson and Josh Anderson's gradual climb to becoming 40+ point players. Crouse showed steady improvement last year. 25 in 81 games to 25 in 66 on a low scoring Coyotes team. Watching him play his improvement is evident.
I think playing at a 35-40 in 82 game pace is a realistic expectation for him next season. If he was on a higher scoring team it would be really interesting to see what he would put up. If this trade did happen (it isn't), I wouldn't be surprised if he put up 40+ on the Leafs.