I think the problem is that it's easy to test someone's knowledge of syntax but it's close to impossible to test someone's ability to complete tasks in a classroom setting. To test that you really need in-depth essay type questions and while those aren't too hard to set they're incredibly expensive to mark so you could expect to see the fees go through the roof. Even if we were willing to pay for it the outcome become far more subjective and I'm not really sure we want that either.

Don't get me wrong, I absolutely agree that the "light" nature of certifications makes them pretty worthless at present but I'm not sure it's a problem that can actually be solved. Other prefessions such as Law, Medicine, accountancy etc. put a heavy reliance on membership of professional bodies so maybe there's a solution there but I'm not sure I'd put much faith in those types of bodies as they currently exist in the IT industry. Those other industries have a whole tradition of peer acknowledgement that we still lack as an industry.