I understand that the taylor series used to define sin and cos is a function with a unitless input but practically, a lot of people like to use degrees for the input of sin and cos instead. I hate that it's ambiguous, because calculator software devs use it as an excuse to misrepresent physical quantities like angular velocity, frequency, torque, etc.

Also, it's very valuable to be flexible with the count of base units defined in the system. A lot of software is written with three (length, mass, time), some with 7 (as in SI), and I want to be able to shove in angle as a base unit in anywhere.