Fans of the books please bear with me, I haven't read them but usually villains (even cruel sadists) have some feature of interest which makes them compelling to watch or read.

Young King Joffrey is just a nasty little git.

There is nothing interesting, redeeming, or entertaining about him at all so far in the series.

He isn't a love to hate character he is just a vile piece of work and I can't see how any death, no matter how imaginative would work as narrative payback for what he is.

He is like one of the monsters from Salo.