Sometimes I wonder why more K-1 don't make the move to MMA ans then i remember watching Mark Hunt fight Fedor. Not to say Mark isn't a great fighter to watch or that K-1 sucks, it really is so much fun to watch, but 99% of kickboxers just can't hack it in MMA.
Conversely, you can argue most MMA fighters just can't hack it in K-1. Not having to worry about a ground game opens you up to more options of the feet (look at the ducking and dancing boxers can do becasue they don't even worry about kicks or shoots)