It was nice in 2.0 where a sch/sch team was a pretty nasty thing and it was generally best to to have a whm/sch team. They blew that up with ast and now if you required healing, ast would take the whm spot cause of utility and similar healing output. They're not going to require the healing output cause they don't want to have a specific healer be required. Without giving whm more utility I just don't see anything they could reasonably do to make whm desired in 8 man content.