The first time I read about the "rewind" feature I had to think of one thing: Emulators that have this feature. I use to play on an NES emulator some time ago that did exactly this, I could just rewind whenever I felt like it and try again. What can I say? It utterly RUINED the experience. Nothing I did really mattered because I could just go back in time and try something different. Believe me, if you had this power in real life, it might be totally sweet at first, but I´m certain you would go insane after some time because if everything is undoable, what does anything matter?
And the problem isn´t that you "just don´t have to use it": It´s THERE, if you really screw up badly you´ll go "Ah, what´s one time gonna do, right?" And then you might up using it again and again with the same excuse. One might argue that "Well, it´s just a game after all, why don´t use it the way we please?" A game where you can just do whatever you want isn´t a game, it´s a toy.
Some of the best gaming sessions I ever had was with arcade 2D shooters played on MAME - finally reaching that stage I have never reached before on my last life, with sweaty palms and a racing heart. I did set the game up in a way that simply putting in another virtual quarter wouldn´t work - if I screwed up, it´s Game Over. If I would have known that I might simply continue after that, it would have been a vastly inferior experience. Another good example is the Ghosts`n`Ghouls series: These games get almost all their thrill from the brutal challenge they pose (which some people consider a bit too brutal, but whatever). Again, savestating (which basically is "rewind") completely ruins these games.
I feel that racing sims are very similar to these hardcore 2D shooters or platformers in this regard: They demand that you are concentrated at all times, always on the edge of your seat. If you know you can just rewind whenever you want, suddenly the race becomes a lot less urgent. And that´s why I still play games after all these years: Not for some softheaded entertainment, but for this feeling of concentration, urgency, reward and relief.
While I am far from being a racing sim purist, this rewind feature really only achieves one thing: It declaws a majestic, challenging experience.
Keep in mind that this doesn´t have anything to do with being a "tough guy": You´re robbing YOURSELF of a valuable experience. Failing in a videogame can be frustrating at times - but it´s this very real pain that makes overcoming the challenge that much rewarding. You wouldn´t believe how many people play games like Ikaruga, R-Type (or whatever is the most well-known 2D shooter to the mainsteam gamer) and people just go "DUH, you can just continue through the whole game at once, it´s over after 20 minutes, what a rip-off" while completely forgetting that these games are meant to be mastered, not played through in the least challenging way possible.
This applies to real life as well: Frustration, disappointment and failure are NEEDED to grow as a person. If everything would be handed to you on a silver platter, you would become a spoiled, bored crybaby with a overblown sense of entitlement. Sure, there´s some brainless games out there that mainly are meant to kill some time (The Sims or whatever), but games actually can be a good training in patience and stamina - if you learn how to deal with negative emotions. Hell, if a game doesn´t slap me in the face sometimes I won´t even properly respect it
/rant