If you were able to hear just the exhaust in isolation on a real car, your opinion might change - that's quite rare to find in recordings, though, and only truly accessible through simulation. The tunings do however represent unusual setups, purely to account for missing sources - but they are physically possible for the most part.
The main reason for "weirdness" in the new exhaust sounds (aside from the massive issue of missing sources), that causes the drop in fidelity and listener fatigue, is what PD call "phase noise". That's purely there to stop things sounding too smooth, but with a few more cycles you can use a more physically based method (e.g. a turbulence model) instead of just plain "randomness".
So in order for the sound not to be too "digital" (like old
AM synth), they add noise, but then it sounds too "digital"... Still, crunchy distortion is better than hollow square-wave vibes, because one is more like real exhausts than the other.
PD are doing an excellent job of synthesising exhaust sounds on the fly, and I can't wait to hear the result when they get intakes working, too, and all the extra filters they've yet to enable. Then it's all about the customisation.