^^ Take a deep breath, slow down, wipe the sweat from your brow
I think that reason is exactly why Jackson shouldn't have been Mace, it's not about being cool but being a spiritual leader and warrior, this isn't 'Kick Ass' we're talking about, I think the role needed a more serious casting, more gravitas and wisdom basically. Jackson looked the part but his personality isn't right, a young Morgan Freeman would have been perfect in an ideal world, but for me Washington would have done it spot on, he looks strong and worldly, wise and epic.
^ Your right about him looking uncomfortable too, in the greenscreen shots and lightsaber fights he looks hilariously bad. Again I must refer to 'redlettermedia' as he made a valid point, Lucas only cast Jackson to appeal to a young audience (mainly black obviously)...hence the 'cool' factor rears its ugly head again.