Are we really that uncertain about AGW than other standard theories?
There's a bit of a false comparison in your question, as AGW is (in scientific terms) a hypothesis, not a theory. Unlike the AGW hypothesis, the "standard theories" you're comparing it with are actually supported by strong evidence.
As for the level of uncertainty in the AGW hypothesis, it is enormous. In fact, that was one of the clear revelations in the Climategate emails -- to promote "the cause" (Michael Mann's words), the climate researchers have been downplaying and hiding the huge uncertainties.
The reality is this:
-- While a slight bit of warming has occurred in the last 135 years (about 1 degree C), there is no evidence that it is unprecedented or unusual.
-- There is no evidence that man-made emissions were the dominant cause of the warming that occurred in the latter part of the 20th century.
-- The predictions of how man-made emissions would affect the Earth's temperature in the 21st century have been spectacularly wrong.
The last point is particularly important with respect to your question.
You test a hypothesis by making predictions and then measuring the observed data against the predictions. The fact that the predictions have been so spectacularly wrong is good reason to think the hypothesis should be rejected.
At the very least, we should acknowledge that the science in this area is far from "settled."