You speak very truly. If an anime (Historical) contained only the material for the most accurate telling it would be very bland. But on the other hand. If an anime was tell a story in the most accurate way possible, it would first be uncensored. When it's uncensored then obviously violence galore. I will say right now, violence in a History anime should not be dumbed down. Simple biology explains the reaction of violent disruption to flesh and bone. So it already falls into an Action, History sort of thing.
But I must say the Historical anime 100% depends on what article of history is being told. The Iliad by Homer. That if put into an anime, would be and action, adventure, mythological sort of setting. That would be an interest to many viewers. Now if the telling of how the Shogunate came to be. That could be a little more bland. Mainly recounts of skirmishes and heroes grown old. That to most viewers would be a failure.
I am fairly confident that when making an anime, the producers know of this and introduce an add-on element to attract viewers, but without destroying the image of what they are trying to create. Like as said earlier "Ecchi" It is a tease. Mainly for men. But what will take down an anime really fast in my opinion is when Ecchi is used excessively and any historical meaning is lost. This also goes hand in hand with fights. If you got women, you need guns, knives, swords! Then you fight! That does not appeal to me. Some creators realize and fewer balance it out evenly enough.
Realism is a must. It must not be sugar coated, stretched and pulled. That is what gives a good ground to an historical anime. Hey was that, just now the sword known as Masamune? In reading, it is a legendary healing sword. So thus gives ground that this certain kind of anime is real. Or very close to the real world.
Everything I have said here goes the same for Manga. I like it sometimes with a little twist or some third element not mentioned in the books, but yet put in check with a fourth element called truth. That element sadly does not exist in most works now.
I must now retire to my bed. I have no idea what time zone you are in or where you live. But over here it is now bordering 2 in the morning. I have to be up 6 hours to do school work. Goodnight, Mr. PhantomZwei.