This will be an ever lasting discussion.
If Scawen is working on phyiscs (and this takes a lot of time to get it together in the first place and then get it right after that) people are 'moaning' about wanting more content.
But if Scawen/Eric would decide to put time into creating content and then release that, people start to 'moan' about the time the new physics (and therefor release of Sirocco) will be released.
Personaly I think there is enough content in LFS (plenty of cars and tracks to choose from) and even the release of new content like Rockingham (or updated Blackwood etc.) made people bored a few weeks after that.
Bottom line is that Scavier will never be able to put up with the developement pace and budgets of big gaming companies (not that they want that, a case for them of been there, done that) so progress will always be (very) slow, compared to companies like IE or Codemasters.
The other side is that the things they do deliver are of the highest quality and if not, they give proper support.
Look at what those big companies put on the markets (half baked games, more like alpha's or earlier beta's), then 'support' that with a few patches to solve the biggest issues (if possible) and then move on to the next itteration of their game.
Read the Codemasters forum for example and see how bad F1 2017 is (which is the case every year) and compare that to the quality you will get in LFS.