"If this is destined to be your only MacBook Pro (which it will be — we reviewers aren’t your atypical Mac owners)" - are you sure, Mark. I think that you are very much atypical Mac owners & users.
As for bulk - my view is that today people are obsessed with smaller and lighter. Yes, there are some benefits for that but also some detriment.
I still use a 2011, last version of the MacBook Pro 17". Despite having to perambulate with the aid of a stick and being physically frail, I have no difficulty in carrying the laptop. (Incidentally, from where did that 'laptop' designation arise? I've never used one on my lap, yet.)
I do find a major benefit with the 17" screen, however, and that is simply its size. I have poor eyesight, (yes, I *am* dilapidated and even more dated than my Macbook Pro), and do a lot of database and spreadsheet work. Small screens are a real impediment to ease of use for me. The 17" is, at least, useable.
Incidentally, that raises another issue for me. Certainly meaning no disrespect or criticism of you or other reviewers, I rarely if ever see any recognition in reviews as to how suitable the product may be for people with a disability. Perhaps that is something worth considering for the future.
Regardless, thank you for your continuing interesting and friendly reviews.