if the majority of the league has a problem with it then it's a problem. as for safety play, i'm not sure what you don't understand about being able to cover a ridiculous amount of field with one guy.
you want to look at boxscores and stats to prove DT play is a problem but you don't realize that a lot of the things that someone can do with a safety and his roaming ability would NOT show in a box score. things like:
1. run support where you dont get the tackle but change the RB's path
2. pass support where people won't throw to a receiver who should be open because you can cover so much ground so quickly
3. passes that are simply knocked down instead of picked
i won't shoot down any ideas on how to make the league better but i usually don't like so many restrictions on gameplay
My counter argument is that while the safetys CAN cover more of the field than usual, user controlling that position and making the wrong move can very easily lead to a touchdown. The risk/reward is almost even.
IF you fuck up while playing DT, 95% of the time your problem can be covered up fairly easy by a linebacker or another lineman. High reward, low risk.