Good points on the theatricality of DS. Very true, and many of the aspects you describe are among the reasons I've been devoted to the show (the theatrical aspects you talk about, though not necessarily the occasional over-acting).
Many of us have been writing appreciatively about the show for many years, including the acting of the core ensemble, often relating it to a particular actor's theatre experience (e.g., in my case, I think I commented most extensively on Jonathan Frid when I began posting four years ago), so hopefully no one is getting the impression from comments in this thread that any one of us is saying the acting on DS is bad, period. Quite the contrary, but you would probably need to be familiar with many previous discussions.
It might be worth noting that even some actors who most of us admire, such as Grayson Hall, said she thought she was terrible on the show. Obviously, I don't think she was (except maybe in her first episode or two), and I appreciate her more now my second time through the series. But it's interesting to consider that actors often have a more realistic view of their own performances than worshipful fans sometimes do . . .
Personally, in making my comments I do have maybe half a dozen performances or periods of the show in mind during the course of its five-year run. If you watch it all, you will definitely see actors breaking character (one was fired shortly after he did so, though he was actually a good actor and better than his replacement) . . .
But I have no desire to start naming and listing these . . .
. . . hope my VCR is recording David Blaine ...