I have several friends who went onto MBA programs after graduating with technically-oriented degrees (and working a few years). It is a good combo, and I didn't say otherwise. What I say about business school is precisely what they say about it to me.
The rest of my statement was prefixed with "IMO" which should give you a hint that it's coming from a subjective perspective.
Of course the collapse of the financial industry is a part of the problem, and a very visible one. The manipulation of endlessly complex financial instruments is surely the product of some very clever minds. The trouble is, none of this fancy business actually creates anything real. It's just shuffling money around. It's supposed to be an aid to other enterprises, not an end in itself.
You need other enterprises, manufacturing, industry, labs, and academia to actually create real products and new ideas. And you need people capable and educated enough to be a part of that. And you also need managers talented enough to run them. But you don't want a company staffed entirely by managers. That's a disaster -- nothing would get done. When I refer to a glut of MBAs, this is what I'm talking about.
I blame the educational system here, frankly, it doesn't prepare or engage students to the level necessary for proper high-level work or research. K-12 is a zoo, and then you are tossed into some undergraduate program which has to deal with the unprepared entering students rather than focusing on university-level material. (Assuming you even make it this far). It's no wonder that the numbers of American graduates of engineering, science, and mathematical discipline are declining. There are many foreign students who come better prepared and are able to take advantage of the programs, but then after they graduate many of them just return home. We should be trying to attract them to stay and work here. Or fix the endemic problems with the system.
In other words, we need more do-ers and thinkers.