I think I have the same view on all the points you made and want to complement for the way you wrote it 
Would also like to add my thoughts and perspective regarding posts about “stability”. 2 actually.
My first perspective is perhaps generally accepted and understood, its about that because every computer has different configuration on both hardware and software it makes hard to find all the bugs before a public release. Actually I would say while going out on a limb that its rather impossible
Epics own QA can only do so much before initial (minor) release, rest is done with the community/users feedback and bug reports as patch releases. (z in x.y.z)
Interestingly what Epic has done for 4.5 is releasing a preview build accessible from the launcher to catch some of the bugs that Epic perhaps wouldn’t have done without the community, for the minor release instead into the patch releases resulting in better 4.5.0 release experience.
As I said is what’s perhaps generally accepted and understood.
My second perspective is perhaps not so clear and present in our minds (or existing at all :D), it’s about that some thinks that 4.x.0 release quality is a good minor release while others find it lacking. is because that we, the users, have different needs and sets the bar differently, we must understand and respect both ways.
Some find that a 4.x.0 should be as good as a 4.x.1 or perhaps even as good as a 4.x.2 quality release is today. we, the users, have different thoughts about it I guess and to add more complexity and a headache to story is that some user experience the builds differently because of their own hardware & software configuration as explained on first perspective!
Currently one way to go is that you, as a user, should determine for yourself and not for others what level of quality release you set the bar and stick to that. If you prefer a more stable version wait until first or second patch release (i.e. 4.x.1 or 4.x.2) or read the forums and check the temperature.
Otherwise for the future there are two other options for Epic to go with that I can think of:
First option, if we insist on better initial minor releases (4.x.0) we have to reasonably go with 2 or more preview releases and longer/slower development time I guess.
Second option if really really really needed is that Epic introduces LTS (long term support) versions perhaps once every year which might slow down the current main branch due to resources spent on two versions.