It’s hard and not hard to say why The Force Awakens was rated PG-13 but part of me does wonder if it’s due to the backlash the Prequels got for their childlike tone at times.

Strong disagree. Besides, 1/3 Prequels was PG-13 and it earned it. It’s painfully obvious to me the PG-13 rating for the Sequels is just the result in the standard creeping upwards. Nowadays everything’s PG-13. Look at any Marvel film (kid friendly stuff) and you’ll see they’re all PG-13.

Like the Lurmen were developed for Revenge of the Sith

I did not know that. How fascinating. That explains why they’re said to be native to Mygeeto. The concept art is a little more like just straight lemurs, though.