1. There was no point, having thought about it a bit; a lot of the patches (in essence it was at most a handful) revolved around disabling features which in turn could never have been upstreamed. An example was, as mentioned elsewhere in this comment section, the abysmal performance of the thumbnail gen feature, it never cached right, it never worked right and even when it did it would absolutely kill listings of larger folders of media - this was basically hacked out and partially replaced with much simpler gen on images alone, suddenly the file manager worked again for clients.
2. Guess that's debatable, or maybe even skill dependent (mea culpa), and also largely a question of how comfortable one is with systems that cannot be reasoned about cleanly (similar to TFA I just could not stand the bloat, it made me feel more than mildly unwell working with it). Eventually it was GDPR reqs that drove us towards the big G across multiple domains.
On another note it strikes me how the attempts at re-gen'ing folder listings online really is Sisyphus work, there should be a clean way to enfold multiuser/access-tokens into the filesystems of phones/PCs/etc. The closest pseudo example at the moment I guess is classic Google Drive but of course it would need gating and security on the OS side of things that works to a standard across multiple ecosystems (Apple, MS, Android, iPhone, Linux etc.) ... yeeeeah, better keep polishing that HTML ball of spaghetti I guess ;)