It was not completely wrong if he was right about some things. It's one thing to say someone broke a window and another thing to say who and how and when. He proposed an explanation which know now to be false. But the thing to be explained is still there.

Sad thing is that much of the literature in philosophy of mind will discard dualism solely on the fact that past attempts to explain dualism have failed. And more over, some have just failed to convince the opposite side, which is open for subjectivity.

Oh, for sure. Aristotle is an even better example. Doubtlessly one of the best minds on record, and yet he came up with a "completely wrong" model of the universe. Really makes you question what we are so sure about these days, and also what it means to be wrong - Aristotelian physics worked well enough to be useful for a thousand years.