Under Admin > Email I included tokens for From Email/Address and From Label/Name:
But is there a way to bring in a {{my.Email-SubjectLine}} token by default (automatically)? What's the rationale for not having field in Email admin settings?
One of the reasons might be that since every email must have a Subject line to be approved (forcing some level of human intervention) you'd be skipping over that check if you had an inherited Subject token.