I was NOT directly involved in F-35, so I can't speak to the exact amount of sleaze that occurred with the prime contractor.
I'd love to see a real competition! (new contractors, new ideas, new teams, new airframe ideas). And two engines, yeesh.
Anyways, cost plus is great at moving risk to the government. FFP is at the other end of the spectrum, moving all risk to the contractor.
[Unnecessary edit: I'm a fan of the textron scorpion-as a light attack fighter we could modify]