The 13-inch Macbook Pro (without touchbar) has only two Thunderbolt 3 posts. Connect an external monitor and an external charger, and you can't connect an external hard drive without unplugging one of the others.
The Mac mini has 4 TB3 ports + 2 USB 3 posts and HDMI for monitoring. Also it has 4 more CPU cores and doesn't need an external charger.
Which make it more practical.