Yes, "maths" is more logical, it being short for "mathematics", but that still leaves the question of why the "s" is there in the first place.

There are roughly a hundred singular nouns ending in "ics" in the English language. "Mathematics", "physics" and "economics" are a few of them. In most cases the same word without the "s" is not a noun at all, but strictly an adjective. One can study economics, but there's no such thing as an "economic". Calculus is a branch of mathematics, but I've never heard it referred to as a "mathematic".