Since this is sort of a sensitive subject let me start by stating that:
I like LFS just as it is. Other sims have real cars and tracks which is really nice. LFS doesn’t but it has other features that makes it great too. I don´t think any one sim is ever going to be perfect, and specially not for everyone. Every game/sim has strong points and weak points. Use the one you like or buy them all.
Mods can be a good thing or a bad thing, I´m not getting into that though.
Any decision the developers of LFS make is ok by me since it is their game anyway and it is up to them to decide how it should or should not be used by the people they sell the licenses to.
Having said that I really don´t get the logic of not being able to chance car shapes.
You can change all the specs with Tweak or Makanic, making a FXO have the same specs of a real car, a street car or any car for that mater. You can even make the FXO (or any other LFS car) into a sort of monster with absurd specs, undriveble, if you so decide. You can exchange those specs with people in this forum. Of course you can not use this beast on line but still that is not what LFS was meant to be. So in a way you are messing with some core values in LFS.
But, that is ok and legal. People talk about it freely here.
Now if I had the knowledge to put the shape of a car, not a real car even, but a shape that I made, in the FXO that would be illegal. Even if I kept all the specs of the FXO. Notice that there is no copyright problem here, I create a shape in say 3DSMax. Even if I don’t use it on line the is a taboo, illegal even to talk about.
Why the prejudice against shapes and not numbers? Either both should be illegal or both legal. I just don´t get the logic.