I think both ways (commissioner power and league votes) work, and if you're the commissioner you should do what the league wants in terms of what system to use.
I keep hearing about how all trades or most trades are vetoed in the league voting system. I've been playing in a bunch of leagues with league voting systems for the last 3 years. Out of all my leagus only 1 trade has been vetoed with that system.
Bluto: Over? Did you say over? NOTHING is over until WE decide it is! Was it over when the Germans bombed Pearl Harbor? HELL, NO!
Boon: Forget it, he's rolling.