For some techies, the very notion of taking piles of extra classes to learn about what they (those other people) do is abhorrent. Most of us prefer the bits 'n' bytes, some even to the point of preferring to be left alone with them. In the real world, though, most computing is driven by and deployed for business needs. Getting any business degree, especially an MBA, shows an individual is interested in how computing impacts the business and how an organization can derive value from it.
Additionally, an MBA shows that the IT person in question is a bit more well-rounded than the average stereotypical techie, and can contribute to the overall goals of the company.