I use Kubuntu LTS, sometimes I had to compile a program that was abandoned and I wanted to keep using it. In the last year though we get snap and flatpacks so in theory this could work in future unchanged(though you can't be 100% sure). About the icons, good developers use the system icons so installing a different icon pack compatible with GTK2 would solve the issue(not if the developer included his own icons). About OSX , I think they just dropped 32bit support so I suspect you would also hit issues where your old favorite application is broken,

I understand the frustration with tech , I also went for a short while to Windows10 then I went back to Kubuntu and not even dual booting anymore, the largest frustration I have at this moment is sometimes my video card crashes and I am not sure if is the NVIDIA driver fault or is an hardware issue and on top of it people would say "Why did you bought NVIDIA ?, AMD is better" but at that time I bought my card AMD drivers were shit and most Steam Linux games only supported NVIDIA.

I would also blame developers, the open source and proprietary software developers want to use latest and coolest thing, then sometimes they are forced by deprecation of old tool kits to change (at least sometimes GTK2 apps are ported to the better Qt toolkit)