That's not how the game works. The E8 can and will reliably beat p4s where the m4 is disadvantaged. The E8 is even more valuable against okw where the medium tank match up leaves usf on the back foot.
USF doesn't want for AI anywhere so it's lower AI isnt the end of the world if it denies your enemy tank supremacy.
The issues lie in it being doctrinal, and it competing with the Jackson for an AT role. Those and the fact the tank isn't really that FUN (this I suppose is in part because of its lower AI)
Like I said, make it a limited to 1 command unit and it gives it much more room to be unique and not overlap so much. As I think, it might be required to be HARD capped at 1per game due to the crew, or at the very least with an extreme cooldown to prevent stacking up.
But back to your point there is no denying that the E8 has good stats. It can bounce all standard AT and requires a Panther as a means to guarantee penatrations. This is undeniable. There is no spin. Stats are stats. E8 CAN bounce even pak shots at range (the chance is slim but it CAN) it is one of the only allied mediums in the game that has that chance. It's not debatable. It's one of the only allied mediums that can bounce shreks. Again, this is beyond contestation.
The tank is underwhelming. I agree with that, but imo it's a fun factor not a Stat issue. This is not fact but opinion.
Only in 1v1. If anything, the E8 can be useful in 1v1s. I'd still take OKW P4 with better armour and non doctrinal than E8 any time of day. Getting E8 to fight P4s is one of the worst investments one can make in anything above 1v1. Reliably beating P4s means nothing. There will never be a scenario where your E8 and P4 will go mano-a-mano on some wide open space without any supporting stuff. So yeah, in a vacuum, E8 beats both P4s.. but only in a vacuum. In my opinion, E8 should have been a doctrinal premium brawler, not a retarded Jackson that it is currently or just a retarded M4 that it used to be before the patch. And don't give me all that "faction flavour" BS you constantly spill about USF being mobile and whatnot. Those things went away ages ago, in favour of 1v1 symmetrical balance