I call them groove breaks, when the song takes a little break and just grooves for a bit.
The video version of Even Flow by Pearl Jam has a great one, Stranglehold has one, the album version of Sweet Emotions has one as the intro, so maybe not technically a break.
100% agree! RotJ is where the cracks started to show. I think people forget this because all the nonsense that followed, starting with the Special Editions, makes RotJ seem restrained in comparison.