One statement in this thread has puzzled me, that retail floor space is at a premium. In my area, floor space abounds. There are department and clothing retailers who are declining and almost empty. There is empty space on the racks which are farther apart than they used to be themselves.
I have never done research, but I do think it depends on where you live and are able to shop as to what kind of things you can find. When I was 3 sizes larger, I couldn't find pants. Now, I can't find pants. Some weirdness prevails that causes any style of pants I look at to be stocked in every size but mine. And if "my size" is there, it's wrong and I'd rather size up or down, and can't. I take it as some sort of ironic curse, and since it saves me money in the long run, I've learned to live with it.
In a couple larger cities within an hour's drive, the same stores carry a bit larger assortment of sizes. Maybe that is the solution for me.
But yes, since I've shopped for plus sizes with my mother-in-law, I must agree that fit is hard to come by, even when you can get the correct "size" in an attractive style. She isn't shopping for a career wardrobe, but has to alter or shorten everything, so I can imagine if you are short and a plus size, the challenge is even greater.
I agree also with the current trend to shapelessness - I would think that has to do with "fast fashion" even in the designer fashion realm- less cost involved in design, pattern drafting, manufacturing, retailing. Any woman of any size or shape who doesn't want to wear a toga or choir robe for daily wear may be out of luck.