It's fine to get an MBA but don't be an MBAflares up regularly here in Silicon Valley.
Having attended business school at Stanford, I certainly have a horse in the race, but I'm also not one to insist it's (a) the best choice for everyone or (b) required for success.
At the same time, let's dismiss the notion that any legitimate entrepreneur would never go to business school - ie that the act of even thinking an MBA is worthwhile proves you're not a real hacker or hustler.
Key to all this talk is a more fundamental issue which most people gloss over -- the notion of letting an experience define you versus it becoming part of who you are.
And thus my take is that it's fine to get an MBA, but not cool under any circumstances to be an MBA.
Getting an MBA means you're curious to learn broadly about theories and explore how these techniques can be applied to various businesses. Being an MBA means you think you're getting taught the one right answer to problems - to a hammer everything is a nail - and that only MBAs know these dark arts.
Getting an MBA means offering your perspectives and experiences to your classmates. Being an MBA means looking at your peers as networking targets.
Getting an MBA means thinking about your degree as just another attribute of who you are - I have brown hair, a wife, work at Google, enjoy citrus fruits and possess a Stanford degree. Being an MBA means you are "Hunter Walk, Stanford MBA," elevating the matriculation to a level of undeserving primacy.
Getting an MBA means you shoot out of school wanting to prove yourself and see what you can contribute to others. Being an MBA means thinking the world owes you something and that your value 10x'ed just from spending two years on a campus.
At the end of the day, just be who you are, which is a collection of skills, abilities, successes, failures, fears, dreams and hopes. The most important degree you possess is Human University.
By the way, the "get, don't be" applies not just to business school but any accomplishment that causes one to define their identity vis a vis an entity or action. This just as easily could have been titled "fine to go to MIT, don't be an MIT" or "fine to work at Facebook, don't be a Facebook."