I don't think the problem with Halo 4 was so much the deep lore stuff, as it was the game doing a piss-poor job of actually contextualizing what the hell was going on in an elegant way.
Virtually all of the major lore exposition comes via a single infodump from the Librarian, and there's all sorts of key context that isn't present unless you've at LEAST watched the terminals up to that point, as well as maybe even a novel or two. Didact referring to humans as "her pets", the careful reseeding of humanity to ensure they would evolve technologically along certain paths, Didact's relationship with the Librarian, what the hell happened to ancient humanity's empire, what is the "Mantle of Responsibility" and why does it even matter, the fundamental nature of what the Composer and Domain are, etc.
All of that stuff is only explained via terminals, but without it the Librarian's monologue just sounds like a bunch of arglebargle that culminates in her anointing Chief as The Special (TM), when it's much more interesting and complicated than that.
Even the game's end cutscene (which I love), with Didact reciting what sounds like his argument against using the Halo Array to the Forerunner Ecumene Council, would be completely lost on people who didn't see the terminals. Why is Didact talking? Who is he talking to? What is going on??