Is this true though? I'm a tank and I don't need to play perfectly in dungeons in order for the healer to easily DPS. Regen, rouse, aspected benefic are enough to keep me alive even without much mitigation so long as I don't pull too much. I think you need to be very careful with what you think the the pro-dps argument is, and what you think a "non-dps healer" is in our eyes, because you might present yourself as advocating for something that you aren't. A non-dpsing healer IS lazy, we aren't talking about actions so much as we are talking about mentality. They are the people in this thread, and many many other threads who say they won't DPS, no matter what, on principal.
Let me repeat, we ARE NOT advocating that you should still DPS if the tank is struggling and you need to use every GCD to heal, however that is an exception, and in no way a normal run.
Also not true, if you cast protect, then regen the entire party, the chances of you getting full credit are quite high, tanks on the other hand have to resort to DPS or fighting with the other tanks for high enmity.
WHM has regen, medica II, and powerful heals such as tetra and benediction which serve this purpose.
thats why healers have AOE DPS in the form of holy, gravity, and shadowflare/bane. Of course saying "multitarget" is too general to pull any kind of situation from, so it is highly dependant on a case by case basis as to whether DPS is viable.
That is the point. If you changed the dialogue to "do pro-dps healers think that this should be the way the game is designed?" you might actually get some thought provoking discussion in your favour, however the discussion we are having is "what is the right way to play healer right now?" and regardless of whether you agree with it or not, not holding the mentality of DPSing during downtime is poor practice as a healer.
I don't know what you are doing wrong but regen is one of your most powerful spells and should be used often.