Totally fair question. Your description is pretty accurate. The idea behind the milks seems to be to combine the handling/flow characteristics of the splashes with the protection/lasting effects of the balms. The RazoRock products you describe achieve this pretty well; I have both XX and XXX, and I like both of them. I've never been much of a balm guy, but I like the milks. I have a couple of SCS milks, too, and I like them as well. Worth a look. Thicker than a splash, but less viscous than a balm.
I personally don't like the terminology of "milk". I don't know, it just kind of sounds gross to me. I love milk , mind you, but I don't want to put it on my face.