Jesus also taught some pretty radical things, like the fact that he was the son of god, and that no one could be saved from death except through him. There was plenty of philosophy in there as well, talking about loving your neighbor, not judging others, and so on, but it wasn't all just "be a nice guy and you're fine." The bit about him being the way, the truth, and the life is pretty intrinsically tied into everything he said and taught. I'm not sure how easily one can set aside half of what he said while claiming the rest to be solid spiritual guidance.
I'm not a Christian, for the record, though I have read the sourcebooks a few times. :) I just see this spiritual v. religious question now and then, and it really baffles me. Some of the dogma of Christian sects could be seen as unnecessary or extraneous, definitely. But throwing out all of it, and still claiming to believe in Jesus for who he said he was? I'm not sure how that works.