Opening gates can play an important role at the right time.
1. If there is an objective in-front of the gate then we need it open to get there quick enough.
2. If the first gate is broken, we can still stall them at the second gate.
Unfortunately though gates are abused and opened quite frequently and then shut again trapping teams into a death sentence. I think they should try to limit who can actually open and close the gates, but not completely remove the mechanic from the game. They have a useless leveling system right now if they wanted to allow people past a certain level be allowed to use it.
For now though, they have a lot of other bigger problems to deal with before messing with gates. I understand what you're saying though after about 150 games and 50% of those games in siege.