The idea would be not to waste numerous resources and money implementing a broken idea and spend some time coming up with a better one. Why put the education of our children and the careers of good teachers on the line with such a poorly thought out and half-assed idea?

If you think that no time has been spent coming up with this idea, you are coming very late to the party. This debate is decades old, at a minimum. Dates from 1971, says Wikipedia.

http://en.wikipedia.org/wiki/Value-added_modeling

It's not something that "Bill Gates" or anyone else made up yesterday. It's a state-of-the-art approach to a difficult problem. If you have a better way, let's hear it. Otherwise, be quiet.

You: "Yeah, okay, this method doesn't work well enough to accomplish anything and it's ridiculously expensive. HOWEVER, it's been used for decades, and I don't know any other methods that actually work. So let's continue pissing money down the drain."

You are right in saying that if we don't have better evaluation methods, it doesn't matter too much. The trouble is, should we just ignore the problems with current methods? It seems the equivalent of sticking your fingers in your ears and saying, "la la, I can't hear you."

Perfect shouldn't be the enemy of good. Incremental change has its benefits.

In mathematics and logic, showing that a proposed proof is invalid does not require that you produce a valid proof.

In science, falsifying a theory does not require that you replace it with a better theory.