Why isn't Monkey Ball: Banana Blitz considered hardcore?

[Fastrabbit09]

reviews of it say stuff like:

"the puzzle arenas grow increasingly more difficult and later stages are downright insane – hence, although everybody can enjoy the experience on some level, only the skilled and dedicated will beat the title."

 and

"so ridiculously complex and unforgiving that we pulled out our hair until we were bald. If that reads like a criticism, it's not. We put high value on challenging games and we will attest that after you successfully master some of the ludicrous stages in Banana Blitz you will walk away with a real, true sense of accomplishment."

and

"The latter half of the game features plenty of levels with 90-second time limits that can easily take you a good half-hour to get past"

 

since when has 'hardcore' come to not include spending 30 minutes on a 90-second level?  It used to be that 'hardcore' meant difficult to master and beat, not 'full of blood and gore'

is it simply because it has cartoony graphics?  why does a difficult game like SMB:BB get dismissed as a kiddie game and not classified as a hardcore game?