Gates, Jobs, Zuckerberg didn't bother getting ANY degree.
In fact this thread is no different from any general 'is going to university worth it' one. Some degrees at some universities are very worthwhile, and many aren't. The same is true of MBAs.
Incidentally, LSE doesn't offer an MBA, and no half reputable university accepts anyone with less than 3 years work experience for an MBA. Care to give a source for your claim that most people today enrolling in MBAs have zero work experience?
(and no, I don't have one and no intention to, because general management stuff bores the crap out of me. But I do know people who have done exceptionally well directly as a result of their MBAs, admittedly most of them in the US.)