By the time you add external storage and GPU it defeats the purpose: The mini is no longer affordable or mini.
Not everyone needs a dedicated GPU, and some of us need more storage than will ever fit inside a mini.
Apple even highlighted a number of 'pro' uses that are perfect examples of where the new Mini will shine.
Heck, a few weeks ago I wrote an email to Tim (Cook) (unanswered, as expected) complaining about this very problem - there was no "pro" Mac desktop that didn't skew heavily towards graphics intensive tasks.
If you need to edit 4K video, but don't want an eGPU, I'd suggest one of the other two "Pro" mac desktops which feature GPUs that are complete overkill for anything else, or even just a regular iMac?
Not every computer is going to suit every role perfectly. That's literally why there are different models. With the expansion capabilities in TB3 (and I expect/hope, eventually Mac-Mini sized, stackable enclosures, but that's more about aesthetics), we have a pretty decent core machine, that's very flexible depending on the use case.