The lack of progress isn't really LFS main problem. The biggest problem for LFS is the progress other sims have made over the years.
I started playing iRacing about a month ago, and iRacing just feels like it is in a completely different league. I know iRacing is also a lot more expensive, but in my opinion it's worth it's price. I can't even come back to LFS anymore. It's not the physics that's letting LFS down, but rather the amount of feedback LFS produces through the wheel. In iRacing I can feel every bump on the road and feel exactly which bump is kicking the back out.
I am not here to say how amazing iRacing is, I am just using it as an example to highlight the fact that LFS is really lagging behind compared to other sims. nK pro recently updated their game to include wet weather racing, rFactor 2 looks promising, iRacing continues to update their tire model and introduce more cars and tracks.
I have never been one of those people who complains about the lack of progress. But after playing another sim, I just don't see the point of waiting anymore.