I agree that there's a problem of people (even the people who rave about how enlightening it is) misunderstanding that a toy Scheme interpreter is what Lisp is, but I don't think that's an issue with Scheme. Introductory FP classes that use Common Lisp don't leave any better a taste in students' mouths, and real world Scheme is a lot more capable than a toy implementation designed for pedagogical purposes. I don't think the standard's conservatism is very much a factor.