A lot of time when errors are generated because you passed the wrong value, or something changed between versions of the JavaScript API, the error is buried somewhere in DOJO or ESRI code that is practically meaningless. Something _a is undefined...
That makes it very difficult for debugging. While the error might be in our code, we can't determine that without trial and error to see what causes the underlying error.
If ESRI hosted (maybe in beta with and NDA or something) a version of the JavaScript API that was not compressed and obfuscated, we could determine what was causing the error easier. This would also allow people external to ESRI to debug the ESRI code and help make things better.
