I see passengers every day that try to put their bag wheels/handle first, and fail. Usually because the bag is a little too big (23-24"), is overstuffed, or they don't try hard enough. Bringing everyone down a few inches will reduce this.

Now of course a few extra announcements and better monitoring to encourage wheels/handles first will help. Right now the FAs don't bother because there are still lots of overstuffed 23-24" bags out there. A good amount of the time they just won't fit. If we can get to a world where usually 99.8% of bags will fit wheels/handles first, it is easier to get everyone to do it.