There is another reason to use 10° flaps - training.
Many students are not learning to fly a 172, but using a 172 to learn to fly
airplanes. If you are anticipating transitioning up ASAP (as in career
oriented students) it's good to get into the habit, because your next
airplane may require flaps on takeoff, and the one after that certainly will.

I've noticed that airline pilots who also instruct in small airplanes tend to
insist on flaps on takeoff, as a matter of good habit forming. Some also call
positive rate and gear up as anticipated training.

G faris