personally i am a heavy user of inferno setups. I havent the time nor patience to actually set my own setups.
i dont get the WR's with them, and im pretty sure I could go faster if I did put in the time researching and making a setup like the others guys do. like tristan says you need to drive the setup just like the guy who made it so you need to find their WR replay too! then play copy cat! yes I guess that makes me a shit driver or someone who isnt the best but I just want to have close bumper to bumper racing there and then. im not trying to be competetive, I just want to be able to keep up with the pack.
However, in regards to the OP's suggestion of making inferno sets available in-game:
I think it works well as it stands, inferno is a 3rd party resource, but still if you integrated it into the game youll just have a different 3rd party resource show up because all the inferno sets would be standard.