My only issue with making the game harder is that a franchise like this makes a ton of money on it's casual audience. And if they make the game more difficult, then they lose the casual audience.
Casual audiences make more money than hardcore, pro, or intermediate gamers.
For example, on the Wii U. Super Mario 3D World, Donkey Kong Country Tropic Freeze, and Bayonetta 2 all released during separate release windows and all wii u owners had the ability to buy the 3 of them and play them.
Obviously mario outsold the latter two, not only due to brand name, but the difficulty helped a lot. I played all 3 and I Thought that the Mario game was a cake walk.
I keep hearing from a lot of nintendo fans that they didn't like DKCR2 or Bayonetta 2, because those games were too hard.
:/. I admit, those games weren't easy, but that is part of why those games were so damn good.
Birth by Sleep was in my opinion the hardest KH game in the series... How did it sell? Like Bayonetta did. The original KH and KH 2 were as easy as Mario, how well did those games sell?
... I refuse to answer....