Hi Genghis
A number of reasons, some trivial, some less trivial but all my own personal experience & opinion.
* High wing gives protection from the sun & rain when getting aboard or waiting for my student to finish a supervised pre-flight. Ditto about how wet the RHS seat gets if it's raining with the door open.
* Better cabin ventilation. Prefer the wing root ventilation outlet on Cessna's. The Warrior just blows up my leg. If it's really hot the windows can be opened. Don't laugh. I used to teach in the N. Territory & it was worth it!
* I found it easier to teach navigation in Cessnas due to the excellent ground visibility. Gives more time/makes it easier to keep a feature in view.
* C150 & C172 can be very docile or can be made to be less docile with some predictability. A warrior is just docile. I think spin training is beneficial. Can't do that with a warrior.
* Doors either side of the cabin. No queing to get in. Both can jump in or out without hampering the other.
* No wing to slip off getting in or out. In spite of the anti-slip coating.
* It's an easy step up from C150/152 ==> C172 ==> C182 ==> C206 or C210 in handling characteristics. From the C206/C210 engine handling is similar for Bonanzas/Barons/C310/C402. Admittedly the PA32-300 type gives equivalent engine handling going into PA23, PA60/AEST, PA31.
There is a downside with C150/152 when it comes to habitual checking & use of fuel pumps. Tank changes too. A C172 has a L-B-R selector so not so much of a problem.
* I think the effect on flight path of flaps is more readily discernable to a brand new student (ie effects of control stage) than the warrior's or PA38's ineffectual things.
* Handling characteristics in C150/152/172 make it more obvious that coordinated rudder input is necessary when using ailerons. I can demonstrate something like adverse yaw in a realistically & easily perceivable way more effectively in the Cessna.
* Can use the lower surface of the wing as a wonderfully visible teaching tool for AoA referencing eg S&L at varying airspeeds, stalls etc
* The reduced vis. in a turn IS a problem although the up side is that it forces a good lookout prior to turning if the instructor is insistant. It also forces the student to look to the Hz instead of the runway to control the turn eg turning onto base.
* Reduced maintenance/unserviceability of main gear. Never had a spring steel leg need a new O-ring or more gas. Obviously this is common to all these types for the nose gear.
* I happen to prefer the trim to be near the throttle. Provides a subtle pressure for the student to use it, particularly when their workload is high-ish.
By way of experience I have a tiny bit over 1000 hrs in C150/152, about 800 in C172 and a bit under 500 each in PA28s & TB10s + various other sundry types.
I'd take a PA28 before a TB10 though. I think they're even worse!