I think you're right there good sir, we're in a new era of clothes buying. I dislike buying clothes online with a fiery passion, it's just not the same. I will make exception for something I've bought before and simply want another of the same size though.
It's a real challenge when I want to buy new cycling gear for example, ordering online makes sense when it's from a shop that's not local or online-only. I like Decathlon, they do all sorts of stuff I want so I could easily spend a small fortune on the limited amount of times I visit. I still prefer to delay my shopping with them until a time that I'm near one though, I just prefer buying in person. Last year I ordered some dhb bib shorts, no chance of seeing them in the flesh before buying so took a gamble with the size. Thankfully I ordered medium, as they were a bit small in places. Yet the Aldi medium is huge on me (they don't do a men's small when they have the cycling gear on offer, no idea why as they do XL), so I am glad I didn't order small with dhb!
Small size fits pretty well for me with other brands, for example the Adidas running tights I'm currently wearing. Although to be fair, I think with the bib shorts they needed to be medium to factor in the belly. That's rather out of line with the rest of me, but I'm slowly working on that.
When it comes to trying stuff on in shops before buying, I still haven't got used to that being a thing again now such restrictions are over. Truth be told, I always forget such an option even exists!
As for Sainsburys' clothes range, I thoroughly agree. In my local Sainsburys, the men's clothing range is tiny, the children's one bigger and it's completely taken over by women's clothes otherwise.
I would guess you are a bit like me in preferring to get a feel, literally, for the clothes you buy before committing to them. Something can look amazing on a website, but then feel completely wrong when it arrives, and I do not have the patience to try and deal with online returns. All that messing around with printing labels, queuing up for an eternity in a Post Office etc, ugh no thanks!
Kite159 makes a fine point, I don't really buy new clothes at the moment and I suspect plenty of others are the same. I am needing new clothes, but such purchases are being pushed back. Granted, I did have to buy a suit fairly recently, but otherwise the priority is on essential purchases. New clothes is not a priority, I can and will make do! So I predict another big wave of changes to the High Street/shopping centres.