I can see why it should be split. Fighters like Frank Mir, who purposely try to gain muscle mass just to compete with the bigger heavyweights, and also Randy Couture who is arguably too big for lightheavy weight, but too small for heavy weight.
But also the talent pool in the heavyweight division isnt great. Also if there was a cruiserweight division, we may see a few light heavy weights make the transition to that division, possibly dimishing the talent rich pool of the light heavy weight division.
If i had to choose, i'd say not just yet. Let the UFC focus on encorperating feather and bantam weights first and then consider the heavyweight bracket. But not yet.