What happened to the migration button?

Did GGG finally change how HC league charachters die to not add an option to migrate from HC league to SC league? I like that they finally made this change but it isn't really usefull when you lose all your atlas, jun, delve, etc. progress. I could also spend the next 5 hours killing off lvl 2 charachters and not have all my stash transferred.

Do you think it's an oversite, a technical problem or a concious decision?