Kicad can be used version independently, which for my purposes makes it much more reliable, for the projects that I made back in an older version, I can just keep the older version installed separately, ready to roll the moment I need to change an old design, without worrying if there where any changes in between, all the component libraries are separate,
The newer version features are always nice, but if you have a design you made 5 years ago, and it just needs a simple change like a new footprint, the less you have to change to get it done, the better, This is not saying kicads forward / backwards compatibility has issues, just it means you know everything is exactly as it was, as some component symbols / footprints have had there origins and rotations changed in more recent library versions to reflect the standards they now try to meet.