Nobody "wasted" isaacs for burnham. Thay doesn't make much sense to say anyway. There are the actors isaacs and green, characters lorca and michael.
Most of these stories were written or conceived before they were cast. It isn't like the cast isaacs as lorca, and think to themselves "gee this actor is so much better but we don't care cause we have a social narrative to push"
It'd be one thing to say they wasted LORCA in favor of burnham, but not isaacs. The character and the story werr written before they knew exactly who would do the acting.
And my own personal opinion, Burnham is a much more interesting character. I mean even if Lorca wasn't destined to die and continue on, like wilson fisk to daredevil, the interest in lorca's character could only survive attached to michael. at best You can't have Lorca without michael. His character on its own would.make zero sense without michael.
So even saying Lorca is wasted in favor of Michael makes no sense.
I thought there were some episodes that didn't seem to bear out her as a main character but I think its pretty clear the entire story focuses on Michael, especially now. So at best, the Lorca character is only really useful because of the Michael character.