I think the difficulty is less because it's so easy to go through the entire game only fighting the Bosses...
And honestly, what all anti-Cross people say is that Cross had shoddy Character Development (especially, but not limited to, when compared to Trigger) and that's something that is just plain true.
I agree that comparing difficulties is unfounded in a way because CT was easy too, but Cross is more...simple...And I only had trouble w/Miguel (and even then, I only had 1 character KO'd in the end) in CC...Trigger had some difficult bosses, like the Golem Twins (i don't even know the amount of n00bs always ask how to beat them), Zeal's two forms, Mother Brain, ect...But honestly, in almost every RPG, the bosses are only as hard as you let them be by how prepared you are and by knowing how they attack and how to properly counter them...but w/e...