Hunbunqueen

Obviously this is true for a lot of paraphyletic groupings, but I think this is especially a problem for crustaceans because for the most part, unless you are a researcher or a nerd your idea of a crustacean is probably limited to a very specific group of "crustaceans" namely the multicrustacea, or for a lot of people even just malacostraca. The general idea of "crustacean" is mostly crabs and their allies, lobsters, shrimps, krill, mantis shrimps, isopods, and maybe if they are a bit more knowledgeable barnacles and maybe even copepods.

So when most people hear that insects should actually be considered derived crustaceans they are imagining them evolving from a crab, shrimp or otherwise fundamentally multicrustacean or even malacostracan ancestor, when the reality is that the common ancestor of malacostracan and insects would have likely far more resembled various other stem mandibulates and other Cambrian weirdos. Cause that's kinda what the closest "crustacean" relatives to insects are, a bunch of evolutionary weirdos that look more like something out the Cambrian than a modern crustacean.

I don't think anything would fundamentally be lost if people started to refer to branchiopods and remipedes as their own independent groups of arthropods, alongside their hexapod relatives, as something closely related to but not the same as crustaceans.

The obvious question then becomes "what becomes of the oligostraca, aka the ostracods and their gaggle of weirdos" and honestly I don't really understand why these are even considered crustaceans in the first place. Some of the members of this group resemble stem arthropods more than other crustaceans (I'm looking at you tongue worms!) and the group as a whole is basically just anchored by ostracoda, which have an unclear placement in mandibulata might not even be monophyletic!