It would be nice to have obvious counterpart spells like fire4/blizz4 and laylines/between the lines to share a single button since they literally cannot be used outside of their intended context.
I'm not going to lose sleep over it though, I have enough buttons for everything.
I've also had since heavensward to get used to BLM too, not that it's so 2deep4u complex that you need three expansions to learn it.