Another thought I've been having is it feels like a certain general vocal audience kept yelling "Tuning! We want tuning back!" when GT Sport was around and Polyphony heard that. Except I think when a portion of those people say tuning, what they were referring to was sticking 12 turbos on a Swift and going 300mph and doing wheelies. Or making a 1000hp GTR or Supra and winning every race with it.
What GT7 feels like, for me, at this point in time, is that yea you can throw on a bunch of parts, but it might not handle well out of the box. Which is generally a real thing. Taking your car and slamming it on the ground doesn't just overall improve everything about a car. You'd have to get involved with math (yuck) and your cars suspension geometry etc I know some people have already been saying this earlier in the thread so this isn't an original thought.
The last couple days I've spent some time taking a couple 700 cars, my 996, GT350R, and R32 GTR (note: 3 different drivetrain layouts) that I've put together like race cars and did a bunch of laps around Laguna Seca practicing and messing with them. Most recent was the GTR; I had my own tweaks but it was hit or miss. I tried praiano's tune and, frankly, didn't like it very much. But using his as a baseline, I made my own adjustments and I'm really happy with it. I think the most important, impactful thing you can adjust right now is the LSD settings. Every time I've adjusted that or used Praiano's setup, it dramatically changes the behavior of the car. I also spend too much time watching the replays of me doing lap after lap around an empty circuit, because the game is so damn good looking, but it also lets me watch how the car is moving, the suspension, the dive, when I go over rumble strips or smash into huge curbs. I also think the "Measure" thing is not very useful because it doesn't always necessarily give you feedback that what you're doing is changing the car. You need to go back out on track and do a lap or two.
Edit: Another thing you can do is some of the weight reductions w/ ballast. Race cars are typically gutted and often use ballast to reach a minimum weight requirement. So you can try and look up the weight specs for certain race cars, find that Stage 3 Weight Reduction (which I believe is the one that guts the car) will put you below spec, then you bring it back up with ballast and then you can reposition the ballast to give you a better weight distribution (use the Measure tool and left info bar), which the game seems to factor heavily in the PP rating. I assume that means weight distribution plays a decent part in the handling characteristics.
I've been able to get all three of the cars into the 1.26:xxx range on Laguna Seca (on racing softs) and they feel much more comfortable to drive. The GTR, seeing as its the latest one I did, it was actually better to drive with TCS off now.
Also for the first time last night, I finally got around to doing what I did back in the older GT days, and just took stock cars on Sport Hards out to Tsukuba and saw what sort've lap I could put down in the spirit of Best Motoring. Like building my own Time Trial ranking list. So far, the Evo 5 and MK4 Supra felt excellent. Excellent as in pretty damn easy to drive and smooth. The Supra is still a boat. In some ways, easier than all my "tuned up" stuff.