The problem is the constantly changing numbers and who is fighting who. Changing one setting may work with 100 players all fighting on 3 fronts, but those same changes wont work when its 2 teams vs 1, and if you change something to work for a 2 vs 1 setup then it may not work in a lower number situation. Its all just too fluid. With much higher numbers things seem to even out on their own better, or you just dont notice these issues being more busy/active in the action.
A fix is to build a "watch dog" program that watches a number of parameters such as ganging one side, hording, side switchers, ENY of a team getting ganged, and so on and have it auto adjust these things as needed. A big horde is hitting a front, watch dog sees it, adjusts how much damage a town building takes to drop , and displays a system message " Knight town building hardness has been increased 10% on the Bish front." Which like ENY would make it harder to drop the buildings, but if the horde breaks up Watch Dog would see that and return the hardness to normal levels with a new message. That way the fixes are as fluid as the arena. Would Hitech want to invest that kind of time? Dont know.
Id love to see the old AH2 towns added to the maps in a random way, but I think the town are "part" of the compiled map so you couldnt change them on the fly. Only way I think it could work would be to make 5-6 copies of a map, change the towns out and and recompile it. Then when the war was won and that map came up next you could set a randomizes to pick one of the 5-6 maps and present it as the new map. This way maps would have surprise town setup....until everyone memorized them

Just another little "spark" to keep things interesting.
I think the old Dot dar should be brought back. This "know all" radar does cause a lot of "ganging". Also the GV site difference could be closed up a couple hundred. After all a stopped vehicle is nearly invisible as is, gives you a chance to spot them better while they are moving.
On the other hand almost changes are going to cause issues and that would lead to more changes, or just more complaints.