Yes, much easier to control a single variable.

I'm a type 1 diabetic on multiple daily injections -- a pump just introduces a lot of inconvenience for me, price aside. You have to track batteries and change tubing and make sure the tubing doesn't snag on things, and unplug the machine before taking a shower or bath, and ... blah blah blah...

All I need for MDI is to carry my syringes and vial around in a cold pack (I live in the tropics, lol) and I don't need to worry about hardware beyond that.