I do it pretty much every downshift out of habit. It wont cause tranny problems if you dont grind it. Slowing down with downshifts obviously causes more wear on the clutch (only as much as a normal shift though) and thats way more expensive than brakes.
I have always used downshifting and the engine for minor slow downs and such, I only started rev matching because I was starting to do track days and needed to learn the skill so I did it to practice. It just became habit. *shrug*