My first solo and PPL was in our family 170B. Prior to that, most of my time was in 7AC Champs. My stepdad would cover the entire panel with a sectional and taught me to learn to fly the pattern by listening and looking (in both the 170B and Champs). I don't think a student pilot could easily learn to do that in a 180, and it's a valuable lesson to learn early.
(I know bigrenna will love the nice photo showcasing my wheel panties below) [emoji23]

A 180 feels like a heavy dump truck in comparison to the 170. Not meant in a negative way, but it's like a heavy, powerful station wagon where the 170B feels like a lighter, albeit underpowered, sports car.
I wouldn't want to learn or teach primary in a 180. Something simpler like the 170 (fixed pitch prop, etc...) would be way less workload for a student IMO.
It's harder to get a sense of the basics IMO in a big pig like the 180. Again, not meant to be derogatory, but even the early 180's feel like crap on the controls compared to any 170. To be fair, the way a 170 feels on the controls isn't ideal either, but it's "less crappy" than the 180.
For example, I have zero desire to bang the pattern in any 180, but the 170B is light enough on the controls to be fun. The 170B is borderline though, because a Champ or Cub is best for that kind of fun.
The 180 has never been an attractive flying airplane to me, but what it can do is attractive. The 170B is an attractive flying airplane IMO, but its lack of capability is a huge bummer.
Someday I'll add a 180/185 to accompany my 170B and then I'll have it all covered! Oh and I'll have to keep my 7ECA so that I can sit centerline, with a tandem seat, and a proper stick located between my legs. I loathe the dorky yokes in the Cessnas. [emoji2961]