Yes, welcome to conventional thinking. Sauciers’ lack of floorspace (relative to sautes) and lack of volume (compared to both saucepans and sautes of the same diameter) can be a pain. I resold a very good straightwall 20cm saucepan because I found a great 20cm Windsor. I wish I hadn’t–now there’s too great a capacity “hole” between 18cm and 22cm.
“Saucier” was mostly a sales job perpetrated on Americans in modern times. It still sells a lot of them, especially among those who buy into the whisks-in-corners theory. And they’re OK for overall versatility–if you have enough sizes of them or must get by with 1 or 2 pans total. Where they (at least the Windsors) really shine is with reductions–you can reduce larger volumes without changing out saucepans as much, because they keep something closer to a constant surface:volume ratio as the liquid is reduced.
The nomenclature tends to get in the way. We would be better off to distinguish between a splayed saucepan (what most of us think of as a Windsor) and a splayed saute (what some of us call a “sauteuse evasee”, others lumping the evasee with Windsor or Lyonnaise). The former is an excellent reduction pan but usually a cramped, too-high saute. The latter is usually a good saute, albeit with higher sides, but with too high a surface:volume ratio to make a good saucepan. Then there are the curved-wall pans, which are called everything under the sun, but which are also confusingly and indiscriminately called “sauciers”, and tend to have high sides regardless of diameter–bowls with handles. Better we should call those bombees, I think.
Part of the confusion (and makers’ crazy license with language) stems from the fact that there never was a “saucier” in a classical French batterie. And to me, these curved-wall pans, whatever they’re called, are just as bad as Windsors at saute, and worse than Windsors at maintaining constant surface:volume. But man, do those whisks “fit into the corners”, and “saucier” sound tres French (Non?), so it makes us think we’ll be better cooks! Similar dishonest marketry happens with the “Everyday”, “Essential”, “Perfect”, etc. BS the makers spew.
Interestingly, American pans of the 1880s-1930s commonly included a geometry which were true splayed sautes (some of which have cool, swoopy-rimmed canted walls, higher opposite the handle to facilitate jumping), and there are vintage European sauteuse evasees as well. But modern industry has sort of lost the thread along with the nomenclature, and the result is frustration and disappointment like you voiced, else a further departure from traditional meanings.