Should GHC default to -O1 ?

On the haskell-cafe as well as the beginners mailing lists, there frequently (for some value of frequent) are posts where the author inquires about a badly performing programme, in the form of stack overflows, space leaks or slowness. Often this is because they compiled their programme without optimisations, simply recompiling with -O or -O2 yields a decently performing programme. So I wonder, should ghc compile with -O1 by default? What would be the downsides?