You have to have a limit someplace, gameplay requires it. This one is as good as any. Changing gun loads, ord loads, etc is not something that was done in half an hour on a rearm pad. It took hours and was done in a hanger or revetment while the pilot debriefed, ate, napped, briefed for the next run.
All you would really accomplish with a rearm pad change is bigger streaks.
We have people get bent out of shape now because they died with 4 kills. Imagine the whines and complaints if they died with 14, or 40?