Big nerfs on arty in the heyday have really been a considerable factor considering the TD campiness. I haven't really seen reason to revise my opinion. Now, I'm okay with arty not effectively being able to hit moving targets except with splash and even that every other christmas, but having trouble to hit a stand-still AT8 when fully aimed is BS. I've gotten ambushed and two-shotted with Nashorns without ever seeing the bloody big box with mile-long gun more than oneshotted by arty EVER. There might not be map tweaks that will fix that, but the (possible) tinkering with TD camo might at least allow a single answering shot.
Still, I believe there's really a chance that maps will grow more bush and steep hills to hide behind, no matter it'll hurt mobile playstyle. The most vocal WoT community members tend to favor TDs and have at least distaste towards SPGs (or I'm really, really badly reading the forums wrong). At some point SPGs will be gone at this ratio; replaced by arty strikes (gold purchase, of course) and possibly air cover.
Considering SPG similiarities, I've still to wade high enough to notice such thing. Most SPGs I've driven have been really varied and country differences are pretty obvious at lower tiers. Liked french line until nerfs, now favoring british. No boredom yet, must be the pace change in between 5 tiers upstreams scouting matches, manouvering with meds, brawling with heavies and sniping with TDs. I'd love to see that continue, as when the variation is removed, there's only the math and matchmaking.