You mean they add something to make it thinner? No. Huel adds to make it thicker. Not to say gum blends are inherently bad for you, they’re just extra, and minimal.
To be fair, a smoother and more homogenous mouthfeel that neither settles or clumps would probably appeal the the greatest amount of people. Business is business, in the end, and probably why some brands have gone straight to selling pre-mixed bottles. It’s similar to what’s already on shelves.
Water to calorie ratio hasn’t exactly been something I’ve seen mentioned anywhere. Although pretty much every brand goes with the “meal replacement” and “all you need in a day”, 2k calories marketing wordpoopery, as some sort of day-to-day solution, they don’t address how well some would find it at an aggressive surplus. Some of us like to do that. I suspect the vast marketable consumer base prefer losing or maintaining weight. Appealing to them is important.
This also makes sense, but from someone who just wants to buy calories to certain macro and micro values, overconsumption of some values be damned, I prefer caloric density. I also can’t drink thick liquids without discomfort. So a 1:1 calorie to milliliter ratio is one of my highest rated metrics. Aside from that, satiety levels are also pretty important. Then again, I had no trouble being sated on 2k calories of Huel 1.2 UU. Maybe some did.
At some point “add more water” just means “piss all the time”, and I could do with way less of that.