I notice your subject refers to blade width, but your initial post relates to ROH.
BTW, I may be completely wrong about this, but I think most people assume the Eclipse Dance recommended ROH of 1" is a mistake. However, it is true that Dance skaters put a big emphasis on skating fast.
The "Slimline" part of the MK Dance is, I think, only thin in the bottom "chrome relief" section. Most of the blade runner is about the same thickness as many other MK and Wilson blades.
BTW, some of the earliest school figures blades were much thicker than anything MK or Wilson makes now.
AFAICT, school figures is/was generally done at lower speeds over the ice than modern freestyle and dance = so it didn't need as sharp an edge to prevent sideways slippage. Maintaining what speed you had long enough to complete the figure was more important than an ultra-sharp edge.
To confuse things further, small ROH isn't the only form of sharpness. E.g., I was taught to create "foil edges" - specifically, a sharpening lip or burr is polished and redirected into a thin planer surface that points into the ice. (Some hockey players prefer a "flat bottom V" grind, which sort of produces the same thing, but probably not quite as sharp.) In contrast, many, perhaps most skate techs deliberately dull the edge somewhat after sharpening it, the the effective sharpness isn't even as great as a perfect corner between the hollow surface and the sides of the blade would be. And "dovetail ground blades" (called side-honing by some, but the definitions of that term differ), in which the bottom-most portion of the blade is thicker than the portion above it, lead to a thinner edge angle, and therefore also increase effective sharpness. I'm not sure whether parabolic grinds (in which the middle length is thinner than the ends) also effectively create sharper edges - they have that type of effect in skis, but the thickness change is greater, and skis have a "camber" which means they flatten as the weight load increases, which helps skiers make sharper turns.) I also think that a microscopic raggedness of the edge might help make an edge act sharper, but can offer no evidence for that at this time.
Does that confuse you? Oddly enough, although people have been ice skating for quite some time (and probably skiing, sometimes on ice or icy snow, for even longer), not everyone agrees which blade and edge shapes work best.
So blade manufacturers try to meet the needs of a diverse community by offering diverse blade models, with different characteristics. That also helps keep prices high, because there is less competition within a given blade shape.
BTW, I switched to 3/8" ROH, because I found a sharpening tool that produced that, and I prefer to sharpen my own skates. But that is a smaller ROH than I might prefer, so probably slows down the blade a fair bit, and reduces glide time.