Because then you'd have uncounterable unit on field?
Also, panther DOES counter ALL TDs in its range, because its shoots faster/just as fast while having 50% more health.
The entire point of going T4 and paying 185 fuel for a Panther is to get a unit that beats every other medium 1v1, no questions asked. The problem is that there are 4 combined issues, lower range, nothing great moving accuracy, mediocre accuracy and painfully slow rate of fire on a 75mm gun. The design of the tank is fine, but how are you supposed to use it? Sniper from range? Can’t, no spotting ability like su85, low range/rof/accuracy. Brawler? Low rof and accuracy missing shots from point blank. Ambusher? Can’t finalize kills due to low rof, gets no camouflage and can’t stun. Diver? Accuracy sucks. Diver is probably its best role honestly, that and brawling with heavies, which is not what a medium TD should be about,
I think the best fix for the Panther is premium accuracy, make it a very accurate tank able land shots with high accuracy, while also giving it maybe 10% moving accuracy with vet. That would make it much easier to use in space as a fast mobile zone denial tool with great offensive potential.