What I don't get is why ampere is a fundamental unit while coulomb isn't. I mean, it seems more natural to think of amperes and coulombs per second rather than to define coulombs as the amount of charged carried by a 1 amp current in 1 second.
Now, in the abstract, yours is the more natural definition. But experimentally, it turns out to not give the best accuracy.
I believe one starts with (1) the meter (which is based on a second defined using a atomic transition, plus light) and (2) the Newton (which is the force required to accelerate the all-important kilogram at 1 meter per second squared). Then an Ampere is the amount of current flowing through two parallel wires required to produce a force of one Newton per meter between the wires.
