I think an aspect of Shakespeare that often throws people off is the sheer amount of concepts being thrown around, both from a grammatical and a metaphorical standpoint. That's just how he wrote; the writing is thick with pretty much every joke and wordplay and reference he could manage to cram in, because that was what people enjoyed at the time. The late 1500s and early 1600s were pretty obsessed with philosophical concepts that were hard to summarise even in long form - not to mention the references to political climates that don't even exist anymore. Add in the fact that a good chunk of the words and phrases he used just straight up have new, different meanings, and that makes for a pretty hard read, even with annotations.

(On top of that, an awful lot of the stuff he's using is either a reference to a reference - like a version of a Roman myth that was well-known in the 1600s, but has become less popular these days - or just flat out wrong by today's standards. Like how in Hamlet, there's parts about pelicans feeding their young with blood, chameleons having a diet of only air, and being out in the open being bad for your health.)

Of course, OP is right in that deliberate ignorance of these aspects of the work is really annoying, and does no good for any of us that enjoy Shakespeare's works. But a lot of peoples' first introduction to the texts are probably going to be as mandatory parts of an English curriculum - I'm in that category, at least - so it's reasonable to assume that they're going to be frustrated with the way it's not the easiest to parse.