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).