You're saying that and I'm getting the feeling that getting the nastiness designed out of the aircraft is a bad thing? I guess it is for training? But not for actual flying when one already holds a PPL?
For reference, I'm 5'10" and about 95-100kg so a bit on the heavy side and I did find fitting into a C152 to be very cramped. If the instructor was as big as me, I think we'd definitely be rubbing shoulders.
We for me its important for the aircraft to display correct handling while your learning after that when you know what can happen and its not just some theory you have read about, then a more docile handling aircraft is better with the wife and kids onboard although for some it won't be as much fun.
In the PA38 there is never any confusion if you are in a stall or not. C152 and it gets a bit mushy, there may or may not be a plaintiff wail from the horn, the controls will be a bit mushy and you will see a increased rate of decent but nothing alarming.
Two broad shoulder types and you can play the shut door game on the Cessna one person slams their door shut and the other one opens. I usually ended up with one arm over the back of the seat sitting at an angle to not encroach on the students space in Cessna doing nav .And pre solo shoulders thrown forward hands clasped between my knees just to get my arms out the way but still able to grab the controls. I always found the ventilation system better on the tommy could handle -10 in the winter and loads of fresh cooler in the summer due to the intake being behind the prop Cessna you had to wait until airborne for the intakes on the wing root to start pumping air in at any speed.
Cessna V PA38 tends to be like marmite with instructors. Most of the ones that didn't like PA38 I always got the feeling that they were poo scared of teaching in them because of the handling characteristics. Which was more a indication of there own handling/ instructing/monitoring skills than anything else.