Let's force all the dominant champs to move up a weight class! Seriously, think about it. These guys don't really want to risk the move up to face another very dominant champ:
Gsp is to small for Silva,
Silva to small for Jones,
And hw doesn't have a dominant champ so bones fits right in the mix.
Let's challenge these guys to move through the ranks of bigger competition!
Do you want to be a f@$%in fighter! 
Totally makes monetary sense not. Ufc is a business nothing more
Hw does have a dominant champ...
Lol at Cain being a dominant champ, he may become one in the future, but as of today no.
I think it'd be an awesome angle for the ufc to promote, warriors so great they are moving on to bigger challenges....