HoTs are mechanically subordinate to shields, they do what shields do, just slowly and reactively instead of instantly and proactively. Moreover shields can be blanketed over the raid while the raid isn't taking damage, and absorb a great deal of raid damage when the burst AoE happens.
A druid would be better at more consistent AoE where shields don't rack up during the downtime.
A good player can change class and play competently.
Switching class because everyone says your old class is weak is different from switching to a different class because you personally feel your old class was weak in your raid comp.