"leave one version completely available (with same-version modules) while working on the next version. Maybe it's just me, but that seems like common sense."

YES THIS /\ /\ /\

I can't complete my 11.0.4 site and I'm pretty sure upgrading to 12.0.0 why be a disaster!  I'm new setting up my site and the LAST THING I want is to have to download older module and then use FTP to get them install.  

Currently paying for UNA cloud $100 and TMDHosting testing things out and as much as I love the platform this is feeling like a breaking point! It doesn't matter how great the platform is if I can't get it set up.

I wish ADMIN would respond.  PLEASE PUT THE OLD MODULES BACK INTO THE APP STORE.