I knew an older, highly successful CXO type who had changed careers from developer into management and gone to a low-tier MBA school in the process who had a hilarious line: "I've worked with a ton of Harvard MBAs, I had to fire every one of them."

Your point about career shift is really where the MBA shines. MBAs should be viewed as a tool for those who are moving out of a direct technical field into management, and MBA students should bring some real world context with them to their classwork.

The problem with the so-called elite MBA schools is they are designed not for people with experience, but recruit those right out of undergrad with 0 business experience. This results in a general graduate population with highly inflated sense of confidence and no actual work to back it up, a very dangerous combination.