But the default signal is one that "asks" the process to quit. Therefore killing it is fairly descriptive. I can ask someone who doesn't know much about computers what "killing" a program will do and they understand.

signal is not a bad name but `signal 123` is far less obvious than `kill 123`. Of course `signal -USR1 123` is far more obvious than `kill -USR1 123` so there are tradeoffs.