Its important to also note that Bethesda has lost more than Rolston over these past few years.
http://bethblog.com/index.php/2007/12/19/inside-the-vault-gavin-carter/ has left and is now producer at 343 industries.
Also Mark Nelson, who was a talented designer. I'm sure there have been others too.
EDIT: ninja-mod. :toughninja:
Far too many to count other notables include the 3 fathers of TES
Ted Peterson, Vijay Lakshman and Julian LeFay
the absolute Creator of TES Chris Weaver who really spearheaded the first games and who we can all thank for what came after
And many more beside Lore writers and so on, some left because the didn't agree with the new direction some left for greener pasture some left but come back and do bits and bobs for newer gamers (and have hissy fits at fan sites when they interview the first group even if the interview was informative and vitriol free
long time fans know what this refers too)