How many times in your life has an errant, random, unexpected serialized variable been the cause of distress?
TL;DRSerialized variable changes are a major problem because any change makes a hotfix client-incompatible, forcing taxing compatibility checks and backtracking; the forward-migration work would also solve this if it succeeds.
I mean, it's crazy. This is the single most important thing. Because in case you guys don't know, every time we do... Well, a full patch is easy because we patch server, client, hybrid, everything goes at once. But when we perform hotfixes, and God knows we've done a lot of hotfixing this year, that's part of our process now, there's specific steps where our live QA team needs to do compatibility checks. And any change to any serialized variable, added, removed, changed the format, changed the data, whatever: incompatible client. Getting our processes in place to catch those before they get introduced is really taxing, because there's always a, oh yeah, also fix this bug, and that makes the whole hotfix incompatible and we can't launch it. So we have to backtrack, change our approach, whatever. And so that's the kind of thing we're dealing with. This will also solve that if we can make it.