I think a big part of why the healer problems aren't as immediately apparent is because I believe most players who heal at all don't play healer exclusively. They don't go through the MSQ as a healer, and they don't exclusively heal in group content either. I think most healers are flex healers, so for them, there isn't as deep of an understanding of healer optimization, and even when things do feel stale, they switch to another job.