I don't want to turn this into another Jackson thread, so I'll keep it short: yes, I agree with you that the Jackson is disproportiinately good considerung its price and other TDs. But USFs other AT options are also probably the worst in the game, that's why the Jackson has to overperform.
Regarding the HP: the unit was a 3 shotter quite some time ago, I think it was buffed because this was unsustainable for USF and the game flow.
Changing its HP would cause a huge avalanche of USF AT rebalance, which I do not think is worth it since we have a decent chance of ending up with a broken faction (compared to an overperforming AT unit in an otherwise AT underperforming faction)
I wouldn't say the usf other option are the worst at all. They are all extremely cheap (barring the Jackson) for example RE with zooks are basicly the cheapest AT squad in the game. Sherman has better than average pen on its AP shells, the 57mm at gun CAN have the highest pen of all man AT guns (on top of highest rof and longest range)
Then doctrinally they have elite zooks, AT variant shermans with great ROF, cheap m10s.... Their options are diverse and frankly decent, but why would you ever build them when all you need is a Jackson?
The only stock change I'd like would be for officers to get elite zooks as well to both make officers more exciting and desirable in the AT role.
Regarding the old Jackson, yea it's old squishiness was an issue, but making it not squishy with hardly any other change is a much worse direction (it's what? 20 fuel more expensive now but still mobile as all hell, accurate on the move, has HVAP with more pen and damage and a crew?)
It would be like saying ost relies on the sniper but is punished for not protecting it so we're giving it another model. But also it has self healing and can shoot on the move.