Yeah, respawning dragons would break the immersion / lore / whatever, while spawning templars / bears / etc. right in your face out of thin air when you are literally just looting the group before them is completely fine
Joking aside, while I wouldn't like to see the exactly same 10 dragons again, because High Dragons indeed are supposed to be rare creatures, I am sure BioWare could come up with something (if they wanted to) - like lesser versions of them, male ones (still challenging tho), etc. etc.
And I bet this is (at least partially) about limited crafting materials, it is one of the reasons I would love to fight them some more.
But this is not gonna happen, we might see one or two more dragons in future DLCs, but that is it, BioWare simply won't bother with this. Honestly, I still love them, still love their games and I think they made some of the best ones ever, but when it comes to adding features to existing games or you know, actually patching stuff that are broken, they are one of the worst studios out there.