Originally Posted by Gary Griffith
Could you imagine in Avengers 2, toward the finale, when the gang is getting beat down by Thanos, if the sky opened and the Surfer came zooming in?
That's actually a fairly terrible ending. Surfer ex Machina swoops in out of nowhere to save the day and negate the 90 or so minutes of our heroes being put through the ringer?
You can't end a movie with anyone other than the film's leads (some combination of the big four) beating the big baddie. You end your film on an emotional high and tie up the three-act structure with the leads overcoming their internal and external conflicts that have been built up, not with them cheering on some Gary Stu-type champion like the Surfer or the Guardians who shows up just in the nick of time
I understand the idea of it sounds cool, haha, but in practice it wouldn't work and would render the film's first two acts useless