On the day Delinquent was revealed, I predicted it would get banned somehow, due to how it could combine with red card to cripple hands. I never expected it to take this long, though - I guess the "Exodia" strategies with the Peeping Red Card really put it over the top, finally.
Lusamine, though... I can only guess that it has to do with the enormous HP Tag Team mons introduced, which made stall decks way too powerful. Considering how Lusamine has been a backbone card for preserving resources for that deckstyle, it could produce 'endless' battle situations that are just ridiculous to play against.