Our version control doesn't really allow us to hotfix past a few-weeks window.
When we release an update, there's about 2-4 weeks where we hold off on putting in-progress stuff into the 'code', which allows us to fix issues. Once we've past that point, we start adding development, WIP kinda stuff back into the game. Once we do that, we can't really go and fix things from the old build, because there's no guarantee that we'd be able to port that stuff back and make it functional.
I'm doing a terrible job explaining this, but I hope it gives you some insight. We have looked at changing how we do things in the past, but we didn't finalize that due to some technical issues.