But I feel like that's the wrong assumption, the implication that dried ghasts needing water in a place without any has made people think they aren't in their original habitat, but what if that's the wrong interpretation, what if mojang is trying to imply that the nether used to be filled with water

Case and point: Basalt

Made with lava and blue ice.. and soul sand

There's not any ice to be found in the nether but there is definitely a loooot of Basalt, and a lot of soul sand, especially where ghasts spawn and where dried ghasts can be found, there's also no other way for basalt to be made aside from using lava and ice

I don't know how valid or popular this theory is but it seems like the nether has experienced something apocalyptic to a large scale to be in the state that it is in now, and that the new ghasts are meant to tell us that they come from a very different nether than we're used to, one with different forms of life, an abundance of water and ice, and who knows what else