There are no truly mindless things in 4e (no non-abilities), so even the gelatinous cube has SOME intelligence to it.
This is clearly a mook-clearing attack, so perhaps my narrativist sensibility is showing when I say I like it. I've seen it a million times in action movies, anime, etc. where one person is surrounded by goons and either glares at them, pretends to call them over, etc, and they all rush at him en masse only to get their asses handed to them.
For it working against stronger creatures than goons, imagine the climactic fight of The Karate Kid where Daniel-san in the middle of a fight starts goofily standing on one leg. His opponent just charges at him because that's a pretty ridiculous fighting stan-KICK TO THE FACE!
That being said, I think the Charm keyword should be added, because the higher level version (that's really not very different) has it.