C152s and PA28s spin and recover in a way which allows the student to appreciate the concept of a spin, and the sensations to be experienced. These types also allow practice at recovery technique. They are suitable. That is not to say they are the best, but they're suitable - they're certified for it.
IMHO, just because an aircraft is certified for something does NOT mean it is suitable!
C152s and Pa28s are not easy to get into a spin so the entry tends to be overdramatic with a hard pull back before the stall is reached, then they do not stay in easily so the instructors patter tends to be rushed, then the spin will frequently degenerate into a spiral dive, so this does NOT show the "concept" of the spin (whatever that is?!) and often results in the incorrect recovery being used as it should then be a spiral dive recovery - and part of proper spin training is showing the difference between Spin and spiral.
Compare this to spinning in something like the Bulldog - entry can be done AT the stall and it will enter a spin without a dramatic nose up inverted entry, it will then stay in the spin, giving the instructor plenty of time to cover WIHIH, much more relaxed. Teaching on Cessna and Pipers is, I believe, one reason so many hate and fear spinning!