[ggchappell]

> I wonder if this is the case because of dedication to backwards compatibility or because the original syntax was based on some fundamental mathematical concepts that are sound and thus don't change the same way most APIs do.

I would say it's mostly the former. I don't see anything unusually mathematical about Mathematica syntax.

Also, a good, simple & versatile syntax was chosen in the first place, so there was little need to change it. The syntax doesn't look too remarkable now, but Mathematica is 24 years old, so clearly some very good decisions were made in its initial design.