I fully understand anyone that justifies doing something with "because I can".
High RoF guns are usually the by product of trying to achieve good trigger resonse but to me, honestly I don't see the point. If you think that suppressive fire has to be loads of shots on target at as high a rate as possible then you're just plain wrong (the sustained rate of fire on an M249 is only 100rpm for example). It's about being able to sustain a rate of fire that stops the target from firing back - if you have such a high RoF on your airsoft gun that you're going to spunk through all your ammo in no time flat then you've kind of missed the point really. 60 rpm is plenty to suppress a target if you can land shots on target reliably!
That said my biggest issue with high Rof monsters isn't the guns, it's the dickheads that usually use them. I know it's a sweeping generalisation but I'd say 99 times out of a hundred whenever I've faced someone with a high RoF gun they've been trigger happy, overkilling, team killing non-hit taking idiots.