Suppression should have a greater effect, for realism and tactical sake. See games like Rising Storm 2: Vietnam where just spamming MG fire in the general area has an actual tactical effect (ie blurred vision). For the most part using MGs for the assaulting side is currently of little value.
Spawn camping/wave timing: Too often you have a player sitting just out of the restricted zone watching the wave counter tick down so they can pop out and drop that RPG on you or something similar. This is clearly unrealistic and annoying and I would suggest that to prevent this, the wave counter tic is randomized to be +/- 5seconds or +/- 10 seconds from the actual spawn wave from the enemy's perspective.
Objective leapfrogging: This is another really annoying one where an offensive team is going for cap B and one or two players head to cap C and sit there waiting for B to cap. As often as not they will be able to cap C before any defenders can even make it to the point (the post cap defensive respawn wave often can't even get to the point in time). Should this really be a valid tactic? Rushing the next spawn point I can see but this one is just another one of my gripes. I would suggest not making the next point capable for say 15 seconds or so after the last cap (and for the final cache point perhaps even longer).
Your tuppence is appreciated.