No, because it would be horrible for balance.
nooooo please don't remove pather for jackson it wuill make ostehr up !1!!1111!
(secretly prepares new Jackson with spotting scopes and hull down)
It's not just this. While a spotting scoped, command-panthered, hull-downed Jackson would be a bit on the "crazy OP" side of things, there's also the fact that Axis has a better set of tools for dealing with medium/high armored units (i.e. the panther). There's the Pak40, Shrecks, JP4, and tons of heavy AT mines. The increased armor for the allied medium-TD (panther) really wouldn't help them at all, when combined with decreased range, RoF, and speed. Meanwhile, the Axis medium TD would be too fast to catch, and would out-range most allied units, short of other TDs.
Basically, this would be terrible, because it would give the Jackson to the side that could exploit its strengths even more.
/edit
Hulldown + vet 5 command panther + vet 3 Jackson:
Hull down: 1.25x range, 0.75 RD
Vet 5 Command Panther:
Vet 3 Jackson: +5 sight, +30% accuracy, -44% reload (combined vet 2 + 3), +30% pen
End result
160 damage
75 range
40 sight
+44% accuracy
2.06-2.34 reload (I might be slightly off on this one)
439.4 (close) to 371.8 (far) pen
853.3 eHP
It could take a Churchill from 100% to 0%, frontally (100% chance to pen), in 19 seconds. It would be absurdly overpowered.
/edit 2
Keep in mind, it would ALSO have smoke (panzer tac) AND the bonus from the P4 command tank (-20% RD). That would buff it to 1066 eHP(depending on if/how Command P5 + P4 stack).
So basically (if my math is right), an OKW+OST team combo would have an incredibly, fast, accuracy, high RoF turreted-TD with smoke, that could ALSO hull down to become one of the strongest stationary TDs in the game.
I kind of want to see someone make this a mod, just to see how insanely overpowered it would be (hull down and panzer tac don't currently work on the M36).