In nearly all of those cases, the content was removed because either the uploader wanted it removed, or the owner of the intellectual property in the video wanted it removed.
In both of those cases, I don't see how this is Youtube's fault or decentralized hosting would be better.
In the first case (uploader wants it gone) you have a sticky situation where loosely managed websites refuse (or can't) respond to requests to remove, which can start interfering with various laws in various places.
In the second case, where IP has been violated, those same loosely managed sites run significant legal risk of lawsuit by not responding.
From the perspective of a content owner or video creator, why would you want your work decentrally stored in places that you can't control it?
The other angles here have to do with monetization, too. When you use youtube, you can serve user aware ads and track who is watching your video as it spreads. If it is self-hosted, your content has been stolen and is enriching someone else illegally.
From a creators perspective I can't see how decentrally stored videos would be good.
Perhaps what we need is a Library of Congress type organization to begin a serious long-term archive of significant portions of this type of media.