The problem is that we assume that it will forever be impossible for a browser to mimic the look and feel of opening a zip file attachment. I'm unsure if it's

The problem is that we assume that it will forever be impossible for a browser to mimic the look and feel of opening a zip file attachment. I'm unsure if it's possible today but most definitely I don't think it's wise to assume it will never be possible in the future. We are slowly chipping away at defense in depth all in the name of convenience.