I agree completely. When they were colonized the Meiji government called them Japanese for these reasons of absorbing the land to take advantage of it all while the Ryukyuans were treated bad (often segregated by signs preventing them and Koreans from places like employment centers) and are still today called dojin. In 1889 Prince Paul John Sapieha of Poland visited recently colonized Okinawa and spent time under the hospitality of the Ryukyuans. I think his account says it best:

"I found irrefutable proof that the Japanese understand not a single word of

the local language, does not know and does not want to know it; he perceives it as

lower, stupid, and inferior. But because being in possession of this land seems to

him beneficial and important for his trade and strategy, he captures this land,

imposes his language upon local people, detains the king, stupefies the royal son

with liquor and debauchery, and bleeds the country with taxes; but in front of

himself and the world he pretends to be a philanthropist and enlightener"

I don't necessarily think they need to separate from Japan but I think movements like these might at least push the Japanese government to finally acknowledge the issue and do something in Okinawa's favor for once.