For the record, such a change not effectively being a nerf is mostly impossible because the only reasonable damage increase (from 160 to 200) with an accompanying ROF nerf would actually increase the TTK for the most common targets (medium tanks at 640hp) even if DPM was kept the same, as the number of shots required to kill such a vehicle would remain the same because of overkill damage. It would be a good way to make the Jackson more balanced (becoming less effective against everything and becoming more specialized against heavy armor) but it definitely would be a nerf and it would require other changes for compensation.
Well, the Jackson loss the glass but retained the cannon for years now so a change like that we could pretend it's accompanying this changes they should have all those patches ago.