I can only contribute with my own experience. Most of the people bashing MBAs outright here, don't have one.
I do, and I got it after I worked on my first small business. The MBA gave me tools that my engineering formation alone did not. I was able to understand and project more clearly what results my actions would have.
Is it a requirement for entrepreneurship, absolutely not! It is a tool, like any other education. You are not required to have an engineering degree to be successful in the technology business (i.e. Bill gates), but it does help.
The final decision is yours, to obtain a credited MBA, it will be an effort (those which are easy, are useless), if you can use the tools, it will time well invested, if you rather experiment your way through, it works too. Everything in life is tradeoff.