The answer? Because some of us actually like tech. There are two types of people who join engineering: those who have been doing it in some amateur form or another for years, and those who are in it because they had nothing else better to do, and it seemed like an ok bet.
The former won't be attracted by an MBA, because they enjoy being in the trenches, working out the difficult technical problems. They derive thrill out of the act of engineering, and that's why they are there.
The latter will inevitably go for an MBA, or go work at some bank in the vain hope that someone will notice him and promote him to day trader status (believe me, many engineering grads work at banks precisely for this reason). They have no real interest nor attachment to engineering, and will simply go for whatever pays the most.
I think the belief that all MBAs are just frat-boy do-nothing is sour grapes. That being said, I do believe that the industry and investors in general have altogether too much faith in MBAs and pure-management types. The company my father works for had its engineer-CEO retire a couple of years ago, and investors replaced him with a pure manager - someone with no engineering expertise, and is a "pure" business type. The company is floundering, selling off assets, and generally in a miserable state. To me the concept of letting non-experts in the company's field manage the company is downright insane, but yet people do it on a daily basis. If you run an engineering company, for God's sake hire a CEO who's an engineer.