Two more 140 pounders:
Ricky Hatton: Horrible showings at 147 and too big to make 135.
Kostya Tszyu: never even tried to venture from 140.

A few other thoughts/examples:
Bobby Cyz
Iran Barkley
Vinny Paz
Darren Van Horn
Joey Gamache

Would ANY of the above group been multiple weight "champs" without the in between weights? Now that I think about it, Ray Leonard even benefitted some by beat Don Lalonde for the 168 n 175 pound titles (won both same fight)!!!