This smells just like another "I want them to play my way" thread. It's tiring.
People, in the main, load up bombs to attack. The concept of attack now requires bombs to succeed in this game and has done since the day they changed the size of towns upward to encourage the use of bombers.
Attacks bring forth gameplay because the simple response to them is defence. The result is fighting. Fighting is needed for the game's success. The reason that each individual might choose to enter a fight would be as varied as the personalities present, but they have to start before you can participate.
If you want more fights then encourage more people to carry bombs. They will then use them to attack something, somewhere. This will encourage a defence, which will encourage an escorted attack etc..
If bombs and perks need any further entanglement then give people who carry bombs more perks, a greater reward, for handicapping their ride at the start of the fight. If you don't like people carrying bombs to "your" field then you already have powerful options. You can kill the ordnance completely at the base they are coming from or quite easily and readily exploit the advantages of the fighter over the bomb carrier and just shoot them down.
If you want more "pure" furballing in the MA you won't get it by stopping bombing or punishing bombers. You'll just get less fights. You will only get that by having an appropriate map in rotation, a la "Donut."
