I don't think the levels in Link Between Worlds were that much more "straightforward" than most Zelda games are. Puzzle-wise, it's not exactly easier or harder than Link to the Past. Actually, a couple of them I found trickier (namely the Dark Temple). It's certainly no Master Quest or 2nd Quest in terms of design, but it strikes me as about standard for the series.
Having more experience with the general style does make it somewhat easier, but it can also serve to backlash if you ever forget about the wall merging (which made the Sand and Wind rupee dungeon a pain to complete on my first two times playing through, because I kept forgetting that I could wall merge when I reached the three-quarters mark, and therefore was wondering where to go from there).
And, again, the combat and mechanics I put down to general game evolution. I mean, Megaman X is easier than the standard Megaman games. Why? Smoother controls and a little more flexibility, rather than actual level or enemy design. Super Metroid was easier than Metroid. Why? Because you could crouch and shoot, and movement and jumping was smoother.
I think the real reason we don't have more "Nintendo Hard" games is because we have games on better systems with better controls and mechanics.