It's still 4 more options for sight range than Americans get. Also shouldn't a "Tank Destroyer" get the first blow as a vehicle meant to snipe tanks, rather than the "Tank Hunter" which is meant to chase them down? You're own explanation is flawed for that reason.
I'm not saying the Panther should be nerfed, but one of the most mobile and durable tank-killers in the game also has more options to increase it's sight than a fragile tank-destroyer which IRL was the one with good sight.
Self sighting TD's in COH2 are seen as fine in some cases, for example the Elefant and SU-85, because both are not highly mobile. The reason the Jackson being able to self sight is silly is because it already has such a number of advantages over the other TD's in the game in mobility. I would be fine with it being able to sight for itself if it had to slow down or it took more damage while "sighting", but it being able to have excellent sight with out giving something up is bad form.
I'm fully in favor of giving more upgrades to all factions to increase variety, when WFA was first being announced I was hoping USF would have the option to hull down tanks as tank crews often covered their tanks in sandbags and what not.
The issue at the moment however, is not that the Jackson cannot see as far as it can shoot, rather it's that it has made all non-heavy tanks useless.