2 major points about the revelation
(1) Tying DFs to
"dreams" now makes sense why it's called
"awakening".
(2) It seems eating a DF means you're inheriting the will of the past DF user.
- Luffy inheriting JoyBoy's will
- Sabo inheriting Ace's will
That's maybe why Roger/Shanks don't want to eat it and be "free".