I disagree with you about GTS being complete too. It lacks many of the things every other game in the category has included this gen, and it's predecessor included. No weather, no night racing, no damage model. Though I don't own GTS, I have played it on my friend's PS4 for a few hours deciding if I was willing to get a PS4 for it. It didn't convince me like it's predecessors would have. I have every other GT game, and I've enjoyed every one of them until GT5 hit and it started losing it's charm. Each game added something missing from the previous game. I bought my own PS for GT as it was the first game like it I'd ever seen. GT2 added so many cars, so many places to race. GT3 released and I bought a PS2 for it. It cut back on content but the visuals and the handling saw huge upgrades. I'd compare it to Forza 5, less of everything, but everything that was there was better. GT4 dumbed the handling down IMO, but the car count skyrocketed, we got the first taste of wet track racing even if it was more of a beta of wet track racing. GT5 Prologue came out and I bought a PS3 for it, it was a demo. In GT5 the standard/premium car/track thing sucked, and the game looked somehow rougher than Prologue. By now I had played Forza 2, PGR, and other racing games on the market so I had started to notice areas the game was lacking in compared to those titles. GT on the PSP let me shoot a UMD across the room when races got tense. After Forza 4 had been around for quite a while we got GT6 and although it's been patched up since release, it really offered nothing new over GT5 other than the revised handling, it's by far the least played GT in my collection because I had Horizon, Forza 5 which was a gen ahead, Grid 2, and a backlog of other racing games I found more interesting. GTS released, and gone are more than half the cars, tracks, an gameplay options. The handling model felt off the first time I played (and I really don't like the PS4's controller), the July update apparently fixed a lot of things but it's not as good IMO as FM7 or PCars2. It is the first GT with decent car sounds, but I wouldn't say it's much better than the first Forza on the OG Xbox (the doppler effect in replays is extremely well done though). The single player is not a complete SP experience at all either, it's clearly a tutorial for the online mode. While the driving school approach is commendable (I actually liked the license tests in prior GT games), it should have been a part of the SP game mode like license tests were, not the entire SP campaign. I loved the weird pacing of GT's SP mode over the years. The funky jazzy music in the messy but endearing menus. Half the challenge in GT was figuring out where the fuck they put shit in the menus. Goofy shit like the car wash and oil change system were always fun too and added a charm to the series. All GTS has over it's predecessors is it's online play and Scapes mode, which to me isn't worth what it left behind. Probably the best addition it brings is finally having a livery editor.
On top of all that, GTS now offers car microtransactions on an incomplete $80 game right after T10 was chased around with torches and pitchforks for the same thing. I've seen people defending it because of free updates, but the stuff in the updates should have been in the game from the start. GTS is just GT with it's soul ripped out. It's not a bad game, but it's not something I really want to spend a lot of time with.