"We teach Shakespeare and Calculus in high school, though those are certainly not the easiest choices in their respective fields."
I'm not sure that's the best argument. In my sophomore year in high school, we covered Romeo and Juliet. At that point, it is fair to say that I had reading skills well above average. I could read original texts from the 19th, 18th, and even to a limited extent the 17th centuries and understand them just fine.
Shakespeare I could make the plot out, but little more. The footnotes assured us that all kinds of funny jokes and puns were being made, but we pretty much had to take that on faith. Seeing the plays helps a bit more because you get the additional channel of seeing real people, but even then we're taking the humor and puns on faith. I suspect that if someone from Shakespeare's time could see a modern production they would consider it atrocious (once they got past the superior delivery technology); places my footnotes assured me were hilarious were usually delivered straight in the videos I saw, as if the actors didn't realize they were making a pun and it was supposed to be funny. Most likely because, well, they didn't realize it.
I question whether we teach Shakespeare as anything other than "the traditional curriculum", and with a desperate-but-futile hope that this will somehow inculcate a desire to be exposed to more "good culture" in the students... fresh on the heels of teaching the students that "good culture" is written in an incomprehensible vaguely-English language which is completely inaccessible without footnotes which assure us that it's good, really, in plain contradiction to the evidence of their eyes. The shock of the literati at the failure of this plan is amusing, but still sort of odd.
I see a lot of parallels to this with teaching high school students C. We're going to teach them a nearly-40-year-old language (might as well be from the 1500s) written to run on computers the size of rooms with less power than the cell phones the students have, with copious verbiage telling the students no, really, this is computing! despite the fact their eyes will tell them their programs resemble none of the programs they actually use? Gosh, how could that ever fail?!
Save it for college.
Just to highlight one of my points, I think one of the worst things you can do is contradict what the students are seeing. They see an archaic, musty language that can barely be understood, that resembles nothing they see in current use, but you assure them that this is the height of Western culture and they'll be better for understanding it. All you do when you do that is blow your precious credibility. I'm sure one or two people will pop up here and insist that Shakespeare changed their lives in school. Maybe one of them is even actually telling the truth, and not just defending the status quo because it's the status quo. But nevertheless, statistically, it's a terrible approach; it can't convert anyone who isn't already very interested and it turns away the vast majority of any who may be interested. I'm not saying we should be feeding our students educational candy, but let's teach things in High School that, when we claim they are awesome, might actually be able to stand up to that point, within the student's actual reference frame and not the "desired" one, which only exists in the educator's head. Dickens, or Melville, Swift perhaps, or perhaps Python or Processing. Jumping to C or Shakespeare isn't done to help the students, it's done to gratify the teachers, and it fails in entirely predictable ways.
A world full of great literature and great computer languages, and we insist on homing in on the very things most likely to turn off the students forever. Then we wonder how schools manage to turn out so many students who hate "learning". Gosh, how could that be?
Edit: One final note. I often get a lot of shock when I question Shakespeare's value. But I think "question dogma" is part of the Hacker's credos. Is Shakespeare holy because you've worked with exposing people to it and seen it change their lives (not just your own, either) and because you yourself love it, or is it holy to you because people have been telling you all your life how wonderful it is to the point that saying "Shakespeare is great!" has become a social signaling mechanism to indicate how cultured you are? I freely acknowledge that there are people who truly do love it... I just don't think they are that numerous.