People should be able to run their teams the way they want. Imagine if Chicago tried trading for Cutler, but other teams around the league vetoed it. 
 
Let's say I have several good RBs, but need help at WR. So I trade one of my RBs for a similar valued WR. Maybe the other guy needs a RB badly, so it improves both teams. Now, if you're an opposing player trying to win, why would you NOT veto this trade? 
 
By vetoing every trade that comes along, it improves your chances of winning, and people do just that. They abuse the veto like crazy, and why not? It's anonymous and there are no repercussions whatsoever. 
 
If you end up in a veto-happy league you basically can't trade at all, no matter how equal the trade is. And you don't know how bad those veto-mongers will be until you've already joined, drafted, ect. This really is the worst part about some of the leagues here. 
 
What about cheaters though? Well, it doesn't even help there. Someone with multiple accounts can time their trades, or just get vetoed and try again and again until it finally goes through. 
 
Here's my solution: Trades go through instantly, no veto possible. Yet, the trade is reported/shown to all members, with a link next to it "Report if you suspect cheating" 
 
The trade happens regardless, but if the person is reported and found to be cheating, all their accounts are banned and they are removed from possibly winning anything. This actually will deter cheaters AND still give regular rule-following members the freedom to run their team the way they see fit.