Well I don’t use any external for “core” storage (ie OS or home folder).
I keep project files (so source code, VM images, etc) on the external m2 I mentioned.
Ive never used a bus powered external drive that hasn’t disconnected randomly at least once in its lifetime. It’s quite annoying when your project files and a running VM are on that drive. I can’t imagine it being less annoying if its your home folder or the whole boot drive that suddenly disconnects.
And of course the oft mentioned hassle of having to carry another device, more weight, it’s harder to use in tight spaces, etc etc.
I use an external drive for work so that when my daily machine has a problem I can literally just unplug, plug it into the laptop that’s laying around somewhere, log in and off I go.