Besides that it would generate ton of forum traffic, gamers expecting some support, and the LFS at the moment is not in *that* stage of development (supporting modders).
It's still too early and many vital internal structures/formats may change in the future, so there's zero official mod support, actually mods are discouraged.
But Scawen already wrote he would like to release some mod tools, once the LFS base will be finished/stable enough (may mean easily another 30y
.. but no stress, there lot of car games with good mod support already, so better make the LFS shine in other aspects first, I'm looking forward for new tyre physics, actually I think we may be only couple of years away now).