Posthumous albums feel... wrong?
I'm not against releasing previously unreleased material after an artist passes away, but the way they handled the Michael Jackson posthumous albums feels wrong to me. They rearranged the songs to make them sound modern and did things like adding the duet with Justin Timberlake. We don't really know how Michael felt about Justin Timberlake or if he would have even agreed to a duet with him. He was a kind person and likely wouldn't have rejected the idea, but since he is no longer with us, it's impossible to know and impossible to get his consent. Even if he had said something positive about Justin Timberlake while he was alive, people's opinions change. We don't know how he would have felt at the exact moment the duet was put together.
It would be fine if they just released a 'Michael Unreleased Collection' or something similar. However, creating an entire concept for the album, altering the sound of the tracks, and bringing in featured artists feels wrong because they don't have Michael's consent for any of it. He cared so deeply about his artistic vision and was such a perfectionist. We simply have no idea how he would have felt about the songs or the concept, or whether he would have even liked these things at all.
An 'Unreleased Collection' would be different because it wouldn't have an overarching concept or artistic vision tied to it. It would feel more like a historical archive.