Hell no. I have a completely unbroken track record of hating every single book that I have ever read for the first time as a class assignment, and have never found that a book I already liked was improved by this kind of dissection.

Maybe I'm the mutant. I know that your reaction is very common, but I attribute it to either the result of bad teaching and/or students being forced against their will to do something that they will therefore be very likely to hate. When I have been in classes with smart, passionate teachers, and the students were there because they were genuinely curious and not to fill a requirement, I've seen lots of minds get turned on in a way that extended past the end of the course and positively affected their enjoyment afterwards. I've also recommended books like Gardner's The Art of Fiction: Notes on Craft for Young Writers to adult friends that are avid readers and have had only positive feedback, some of it of the 'profoundly changed the way I read for the better' variety.

Maybe this is just my idiosyncrasy, but I think making the reader work hard when this isn't absolutely necessary - in fiction, nonfiction, or anything else - is a failure of clarity, not a masterstroke of subtlety.

I don't think very many people would disagree with you on that as a general principle. I certainly don't. Not all difficulty is gratuitous though.