Eventually I concluded the same thing - that the purpose of the class is not to have me actually think, form opinions, structure arguments and express them - despite what they kept telling us! - but rather to find out what the established interpretation is, and express that in a way that looks like I'm convinced by it. Armed with that knowledge, I proceeded with future essays, and what do you know? They were all As.
That whole experience really soured me up on that business, though, because whatever I was submitting for my assignments, I knew it was all bullshit from my perspective. And you know what? In retrospect, some of my opinions I strongly held then may well have been wrong in part or entirely... but they were my thoughts and my opinions, the real thing, and backed by real arguments. And if I were that 15 year old kid, with the experiences and the mindset formed by them that I had, not a single thing would have changed about them.
So, instead of teaching how to think and argue and express myself, they taught me that you conform to what someone else expects from you, and hide your deviations; or else.
It's a good thing they weren't the only teachers...
But that experience definitely steered me away from humanities, and towards math and sciences. There, at least, there was clear right and wrong, and any occasional ambiguity would be clearly highlighted as such and acknowledged by everyone explicitly. And if you were right, you could be as obstinate as you wanted about it; and if you were wrong, you'd be shown a very clear and objective reason as to why.
My solution to that was I never took another humanities class.