Jokers scene I'll admit was pretty screwy, but that was a printing error, not writing
otherwise things like Batmite and the Zur En Rah reveal at the end, of course they're supposed to be intriguing or out of place, or yes even confusing. But just because people don't see the significance INSTANTLY they get up and call Morrison a hack because he writes things they 'don't understand'. Except this kind of writing happens in movies or TV all the time; if you don't get something straight away you just roll with it and wait and see where it goes. But not with Morrison, nooo, if he does it he's a drug-addled pretentious hack.
And no I don't think you don't need the Silver Age issues to understand the basic significance of anything in RIP. They're just historical/continuity context that bring a whole other level for people who do want to know it - and most importantly, I think this kind of writing in comics needs to be loudly applauded, not thrown in the too hard basket. Re-examining abandoned continuity and different portrayals of Batman, the kind of cuts and pacing he's using, Morrison is doing things you can ONLY do in a comic medium.
Otherwise it's simple, Batmite IS either a hallucination or a real-life other-dimensional imp that appears when Batman is stressed out; Batman of Zur En Rah is how he sees himself while he's hallucinating; and the fact he's been hallucinating without realizing it has been made very clear over the last half dozen issues. What's so hard about that. He takes as a name the words that have been tormenting him. Why? I dunno yet, there's still two issues left. I check Wikipedia because I
want to know more but I'm pretty sure that if I didn't have internet I'd be able to follow and appreciate this story anyway.
Also it is important to consider that the easy majority of regular comic readers DO have internet access. So yeah boo hoo for them if they're interested in a story enough to do some 5 min background research in wikipedia

. I dunno, I thought that would be a positive thing. Morrison using two mediums simultaneously to tell one story is to me very clever. I don't see why it shouldn't be admirable as well.