To be clear, this is as intended.
Add the 61% with the 25% (just right folks) and it is close to a bullseye at 86%.
For those who feel it is far too easy, they are correct, and there is only a small portion of the content for them. Still, it is a good bit. Flashbacks open up much of the rest of the game for challenges.
Addressing power creep is one way to keep 'too easy' in check.
Adding new content is another.. but new content needs to be accessible for all, not just a small percentage.
Added difficulty should not have any substantial reward increase, it is just optional.