I think the only people we can blame for that is the dev! Shame on them to allow people who can't pay for a whell enjoy LFS ...
More seriously: The mouse support is a major plus for lfs. I can't count the times i just wish that a game or another include this feature. The way LFS support the mouse is just brilliant and as you said it can "replace" a wheel in a certain way. So when you don't have your wheel and you want to play LFS there is still the possibility to use the mouse and get the steering smoothness. Moreover, if you brake your wheel you still can play (it's, sadly, my case).
Now when you talk about the super steering ability of the mouse you can't say that's a significant advantage. It take a lot of concentration to keep the steering smooth. At the end of a long race i usualy feel tired when i drove with my wheel and it's also the case with my mouse. The bad side of the easyness of the steering is the brake/throttle smoothness inability. So it's quiet well balanced.
Finally, when you see the hotlap and the best drivers of LFS you see that they are always wheel drivers (eg. the winner of the LX month competition who won a wheel was a wheel owner ...). Allowing more people to join the LFS world without the cost of a wheel is a good thing for us but also for LFS.