Yes, even realistic productions have all kinds of artificiality, I am afraid you are not making some kind of revelation here.
There are two major kind of artificialities in film and television. Ones where the audiences notice them as odd, and realize while watching that there is artifice; and then the ones that are the opposite, where they prevent the audience from noticing the artifice.
When you have a clearly unrealistic set, is an example of the former. Or real blind casting which could never be realistic is another. Surrealist elements in the filming, are another kind of example. There are lots of examples of film and TV like this.
It's not simple though - for example, when we watch a play written in the Elizabethan period, the language actually makes us more aware of the fact that it is a play, even though it's strictly more accurate for the period than using modern language.
Productions that are meant to be realist and immerse the viewer have to do all kinds of things, like use modern, but "old sounding" language, or make sure people's teeth aren't so bad they would be distracting, and all kinds of other deceptions that have the paradoxical effect of immersing the viewer.
Both can work and are totally valid approaches but you have to know which you are trying to create or you will do neither well.
The thing with casting that is clearly unrealistic to the average viewer, when you are trying to create a kind of realist immersion, is first of all that it's not effective, they notice because they are not idiots; secondly that you are treating the audience as if they are fools, or an audience for them to preach to, both of which involve disrespect of the audience; thirdly that it does this for political reasons that have nothing to do with the artistic requirements of the project; and fourthly because it treats actors, even very fine ones, as racial tokens.
The fifth reason is that even as a political statement, it's contradictory and hypocritical, because everyone understands why, in a realistic piece, you would use actors that looked as if they fit the appropriate ethnicity if they were talking a story set in India or Thailand or any other specific setting outside of Europe. (Heck, many people don't even like it when you cast non-Asian actors in anime based series that are clearly not at all realistic!) It's extremely disingenuous on the one hand to understand why people dislike unrealistic casting in those settings but pretend not to understand why people dislike it in Wolf Hall.
A lot of production companies now have, unfortunately, put pressure on to tick certain boxes, whether it makes sense for the production or not. Some will not ok productions that do not include certain elements. It's nothing to do with artistic merit, or some kind of artistic vision the production is trying to achieve. It doesn't have anything to do with making sense in the story. People wanting to watch a very well crafted, realist show like Wolf Hall, based on a highly detailed, realistic historical fiction novel, aren't jerks because they don't like that.