Some classes could admit more players like Breacher and Adviser. Actually the max number of players could be bases on current max players in the game, like 1 breacher for every 3 or 4 players for example.
The problem with very limited number of players in certain classes is that occur too many disputes to get in those classes and it become full too fast.

Other classes like sniper would change the game balance if changed so its better to leave them as it is.

Other unnecessary game mechanics is the necessity of the Oberver to be close to the Commander to call for support. It doesn't add much teamwork to the game and just is kinda of annoyance. Commander could perfectly communicate with observer by radio in the game so it can be only necessary that there's an observer in the team and not necessary that he keeps close to the commander all the time.