I have a friend who uses one as his main computer. It works well enough for him. His day job is working as a graphic designer for a magazine publisher, so he uses a high-end Mac with all the latest Adobe software by day and a Mac mini by night, sometimes doing freelance work.
You could use your own monitors, keyboard & mouse on a MBP. Perhaps you have a need for an additional machine? And if so, why not an iMac? The newest Mac minis date from 2014. It is getting a little ridiculous to consider buying them new, especially when the one without the slow processor starts at $699. And the RAM isn't upgradeable, so the prudent thing to do is to get 16GB of RAM to start with for + $200. So now you're at about $900 for a 4-year-old machine with a 1 TB spinning rust hard drive.
A refurbished iMac wouldn't be a lot more money but would be a lot more machine. I know Apple teases the Mac mini at $499, but that's for a 1.4Ghz dual core i5 with only 4GB of RAM and 500GB of HD. I sorta see it as a disservice that Apple is still selling that new.
A good deal on a used one, however, might make the math work out in favor of a mini.