Surely you don't believe that SML doesn't have its own set of issues? My point is he doesn't criticize SML in the same manner on any issue, for a very good reason: he helped design the language.
I believe SML doesn't have any issue that Robert Harper cares about. It is nearly perfect in all things Robert Harper cares about. Are you suggesting that Robert Harper should care about more things than what he currently cares about?
I disagree with your opinion that he doesn't criticize SML because he was involved in the design. SML is not perfect, but Robert Harper does not criticize SML because SML is Robert-Harper-perfect. Or nearly so.
