The consensus seems to be that no one thinks it's worth doing this.  I still think it makes sense to do as one of those latent upgrades that goes in now but isn't active until 12 months from now.   But as you can see from the discussion some people are very focused on overhauling the SIGHASH system entirely, and don't think it's worth the effort to do this small change.  I disagree, but what can I do?