Sabretooth and Mystique were brought on mid 90s X-Factor to try to help save the sinking ship back then. They would have been far better off just making Lorna more complex a character as JM had been doing. Lorna should be able to be a character that can shift between anti-hero and anti-villain if needed, but they haven't sold that in a long time.
Making a fun loving book also dark and provocative is not a simple formula and what they did in the 90s didn't revive sales. I think the current iteration of X-Factor perhaps could have used the investigating horrible deaths function to also be able to deal with the darkest realms of the human condition.