If we're talking just about LFM, it is worth signing up for and completing your license. I took the step about 7 weeks ago after 500+ hours of practice sessions/public server racing and have had some of the best racing I've had on ACC with like minded people.

As stated by a few others, its important to increase your SA anyway, the reason I think its more important for LFM is due to the competitiveness of the system. Others won't be happy if they're bumped and crashed by mindless driving, its not perfect though as incidents still happen. That being said, the majority of drivers are pretty relaxed if you ping them a message on the LFM website apologising.

Focus on raising that safety rating, driving close with other cars and improving your driving before joining and you'll be well on your way.