ST2 licenses purchased close (ish) to the initial ST3 release were transitioned to ST3 licenses - it would have been annoying to have just purchased a ST2 license and shortly after have to pay to upgrade to ST3. We did the same for the ST4 release, applying the 3 year update period to any licenses purchased before the release.
This has all already been discussed at the ST4 launch and I don’t see any extra value in this being repeated again. You can see our official response on this thread.