Major versions are for changing API (i.e. function names, locations etc., anything that usually leads to a compilation error). Minor versions are for changing implementations (i.e. there will never be any new compilation errors; it’s just that the same functions will do different things in the back). Hotfixes/Patches are released when an accidental, known, screw-up (which also compiles) makes it in the release build. I don’t know what this convention is called but it’s a standard which you can find on Google.
Fundamental architectural changes fall into a much more severe category of changes and that’s why you have UE 3/4/5 altogether. It is, indeed, childish to hope to see this change in UE4, but it doesn’t mean the suggestion is wrong nor does it mean it cannot serve as the basis for UE5, when and if that ever becomes a thing.
I, for one, agree with this architectural shift and the fact that UObject/AActor are too bloated and need to be simplified drastically.