Very well said, and the T-rex example is perfect! Yes, that T-rex HAD to eat somebody. That reminds me of the criticism of Reign of Fire (the film with dragons and attack helicopters). One negative review I read said, "If you have dragons and an attack helicopter in a movie, ATTACK HELICOPTER MUST FIRE MISSLE AT DRAGON!" The criticism was dead on.

Too many writers try to get too clever. The flipping tropes thing for its own sake is usually a fail in my opinion. It has to have some purpose other than flipping the trope or all you do is irritate the audience. We're there to be entertained. Everything else is secondary.