Nice rant ;)
I did never have any problems with installing it, but once or twice with upgrading. And I agree with you that the setup is complex with all the possible options and getting it to run well takes some time.
When it comes to the apps, Nextcloud is a very open system. Its easy to publish an app, and the quality of the apps varies. Some apps are abandoned and don't work in recent versions. Personally, I would recommend to keep the number of apps low for stability and security reasons.
I personally have used the cheap ssd prices this year to buy a 4 TB ssd for my NAS. Reasons for this decision include physical space, energy consumption and noise.
However, the backup for my NAS is on a HDD.