You don't need proper feedback to make the perfect sim. Unless you get down to things like quantum mechanics (and maybe even that isn't an exception, who knows) then things are quantifiable. Sure, you won't get as many sensations helping but from a purely vehicle dynamics and kinematics point of view (driver aside), you should be able to get what any human would perceive as spot on physics. Unfortunately we're not even close to that yet as no game in any genre obviously has perfect physics. We're not even close to that in my opinion, some proof of this is the fact that IR, RF2, LFS, NKP, SCE, AC, PC, R3E, KRP, WRS, etc. all behave/drive quite differently from each other (some similarities especially between games based on, or that have evolved from, similar physics engines but even those games are still different thanks to physics engine code changes/replacements). You don't need driver feel to quantifiably view/edit/analyze data (let alone when one can see odd/wrong behaviors which don't even need data because they are so obvious from just visually observing how the physics behave like nothing in reality).
I guess what I'm trying to say is that, in my opinion, the lack of feedback simdrivers feel compared to real-life drivers should have no bearing on how good/accurate/realistic a vehicle physics engine should be able to perform vehicle dynamics and kinematics. Instead, it's all to do with engineers/scientists/programmers ever improving their physics systems.