I don't buy that bunkers slow play. Places where you have to look for your ball, that's what slows play. If they want a design that improves flow, don't include any grass deeper than 3" and don't have any dense areas of trees in play.
A well placed bunker, say 300 yards out right across the fairway, might speed up play in some cases. The longer hitters, who are usually the most wild, will club down to avoid it. A lot of players who couldn't hit into it on one out of 100 shots will also club down because they want to believe they can hit into it. Just not on a par 5, I hate forced layups on par 5s.