I suspect that Boeing's (and Airbus') attitude is that the autothrottle does it (maintaining a given airspeed) better than the human pilot, therefore no need to pad the autothrottle approach beyond a small amount.
There ought not to be too much concern over a modest speed margin, especially considering that the normal 1.67 pad is then further padded by 1.15 (typically) for a wet (not flooded or slush contaminated) runway... provided that the touchdown is well controlled and brake usage planning is sensibly related to the situation.
[ 04 February 2002: Message edited by: john_tullamarine ]</p>