Frontlines has 72 players. Switching has little impact and it's not a ranked mode. Being able to switch willy nilly in a ranked CC match would be completely broken. It would just be constant counter picking jobs every time someone dies. The matchmaking isn't great, but it does take into account the jobs roles. More often than not if there's a tank on one side then there will be one on the other side. Being able to switch at will would break the matchmaking.

It's a stupid idea and you should feel bad for suggesting it. Get good with the job you picked to queue with or go play unranked mode.

And to be frank, if you're jumping into ranked only for the exp....you're the problem.