$\sqrt{-1}$ was completely undefined in the world before complex numbers. So we came up with $i$.
$1\over0$ is completely undefined in today's world; is there a reason we haven't come up with a new unit to define it? Is it even possible, or would it create logical inconsistencies? What would be the effect on modern math if we did so?
You could do this, but you'd have to sacrifice associativity of multiplication. Presumably $h\cdot 0$ should equal $1$, but then $h\cdot(0\cdot 0) = h\cdot 0 = 1$, while $(h\cdot 0)\cdot 0 = 1\cdot 0 =0 $