My Star Wars Hot Take: Ewoks are a good addition to RotJ
They were originally intended to be Wookiees (and really, from the toy angle wouldn't it make more sense for your space war movie to have action figures based on a popular, pre-existing character's species rather than just some generic teddy bear design?) but it was less difficult to find little people actors than 30+ actors who were Mayhew's size, so it's not like the move was primarily made because "They're cute bears who will sell toys! As if we didn't already have a dominant hold on that market with figures and sets and needed something more!"
Also, their relative size and seeming harmlessness actually complement the theme of "Good nature fighting back against Evil technology" that you can see reflected in something like The Scouring of The Shire in Return of the King w/regards to cute, innocent, simple Hobbits fighting against their evil industrial-coded oppressors. It's not like their fight is decisive anyways, they spend most of the Battle of Endor getting their asses kicked all over the damn moon until Chewie and two other Ewoks (you can see how they originally conceived of them as Wookiee's now right?) hijack an AT-ST to turn the tide and give Han an opportunity to trick the guards and blow the shield generator. Like with blowing up the first Death Star, they didn't win through superior fire power or numbers but through teamwork and clever exploitation of their enemy's weak point.
These seemingly cute, innocent creatures divorced from this greater interstellar conflict, who were ready to eat (!) our heroes just 'cause that's how they do hear them out and decide to throw their lives into overthrowing space fascism simply because there were people in need and it was the right thing to do. That is great stuff.
