>If there was an good enough reason for a business undergrad to pursue a masters in CS or engineering, you'd probably see more of it.

It's a cost-benefit tradeoff and you're only considering the benefits while treating the costs equal.

I surmise it's easier for a person without a business background to pick up an MBA than it is for a non-CS/Math/Eng person to pick up a Masters in any of those fields. The learning curves and requirements are different.