I've done the belted blazer (or cardigan) thing, and with the right belt it's not uncomfortable, nor do I find it all that fussy. The reason that look did not become a staple uniform in my closet is that I ruined my garments doing it! Buttons would get sliced right off by the belt, or the garment would pill from the friction.
I like the belt on my Burberry trenches. I don't find it fussy or annoying; I find it flattering to cinch in my waist. But it has belt loops to keep the belt from shifting. Belt loops I had to have raised so the belt hit at my natural waist.
The most comfortable clothes for me to wear are those that fit to perfection. If the waistband is a too tight -- even if it's a ponte knit or leggings or yoga pants -- uncomfortable!! But then there is also the psychological discomfort of having the waist fit comfortably, but the pants are too loose everywhere else and look frumpy and saggy.
Overall, Angie, I do agree with you in general. We have veered too casual. I'm just not sure if it's for comfort reasons alone. It's more complex than that.
Whomever said they remember the days when we wore suits to work and we were perfectly comfortable, is right. I remember those days too. Yes, the shoes were horrible. But aside from that, we had a few impeccably fitted suits and we could mix and match for a full weeks' worth of outfits. The suits breathed, always looked crisp and polished, they accommodated minor weight fluctuations, and most of all... we didn't have to think all that hard about it. Nor did we have to spend hours and hours in stores trying on clothes to find stuff that fit, or in line at the post office shipping things back that didn't.
I really hated it when casual Fridays became a thing. It made getting dressed for work so much more difficult.