Unity also releases with bugs, sometimes even major regressions (75%+ performance degradation on all default UIs in initial 2017.1 general release, for instance

Unity also releases with bugs, sometimes even major regressions (75%+ performance degradation on all default UIs in initial 2017.1 general release, for instance) -- so I'm not sure I can fully buy in to your argument, but I do understand what you mean. We usually bite the bullet just because the pros outweigh the cons -- they do indeed ship a lot of great stuff -- but a lot of problems come with that, too. We still jump when we can (so long as the cons != 75% worse performance on all UIs)! ;)