That's certainly memorable 
I think what draws me to the Kirby Kamandi cover – and bearing in mind that the comic itself was not so great – but that cover has a lot of action in it, there's that Kirby style to the Red baron, everything slightly oversized, everything quite square and that's coupled with the improbable technology of the ride-on submarine and the torpedoes themselves. Oh, and the colour is pretty vivid.
And then there's the strapline about the dolphins – that's quite intriguing – and the framing of the picture on the cover.
Everything about it says "something amazing is going on here", which certainly drew me in. Kamandi isn't a bad comic, and the planet of the apes / boy and his dog themes were also very appealng to a Gamme World player/gamemaster (I got the comic as a back issue – not on the original release).
Anyway, that's sorta my reasoning.