Most of the reasons cited for moving to Python are much more applicable to Haskell and Erlang. Additionally, both languages--and I say this as somebody addicted to Haskell--are too narrow: the perfect introductory language should be able to accommodate both functional programming better than Python and imperative better than Haskell.
Having a statically typed language would add unnecessary complexity to the course; those languages come later anyhow.
Finally, some of the particularly brilliant insights that Scheme gives (code as data and an extremely elegant interpreter in Scheme) are absent in both Haskell and Erlang.
That said, we really should have more functional programming in other classes. I think CMU does this with ML throughout the CS program, and I envy them in that regard. However, this is a different issue; I don't think a language like that would fit any better to SICP than Python.
Having a statically typed language would add unnecessary complexity to the course; those languages come later anyhow.
Finally, some of the particularly brilliant insights that Scheme gives (code as data and an extremely elegant interpreter in Scheme) are absent in both Haskell and Erlang.
That said, we really should have more functional programming in other classes. I think CMU does this with ML throughout the CS program, and I envy them in that regard. However, this is a different issue; I don't think a language like that would fit any better to SICP than Python.