Why? Well, I already do that. I have a MacBook Pro 2017, and I treat it like a MacMini. I don't use it like a laptop. Partially because I have monitor/keyboard setups that I prefer at both work and home, but also because I simply don't trust the laptop to withstand any real usage. The keyboard, mainly. I have two friends with the same laptop, under sane conditions and both have experienced problems (with the keyboard).
So what do I do when I actually need a laptop? I travel with my trusty 2014 (or whatever year it is) MacBook Pro. I love it to death. And when it dies I guess I'll upgrade it. But I've realized I prefer a lesser, small and portable machine for my travel laptop. My "main" work machine is too expensive to feel safe traveling with. My travel laptop is in a separate category.
So when the need occurs, I'm debating hauling a Mac mini between work and home as my daily driver. For travel, it will be a smaller, much more cheap laptop that if I lose/damage I won't be out $3.5k. It just seems to fit my needs better.
On that note, anyone think a Mac mini will survive daily hauls like that? I am concerned that it will be too much movement for a non-laptop. Thoughts?