You can cast longstrider on taller races as well, including wood elves, so they still outpace the small races. For melee classes, it makes a big difference, especially if your build is not strength based (a weak leap also makes a big difference in combat mobility). That lower movement rate is probably why the short races get some of the strongest other benefits, like the halfling Lucky and the gnome advantage on int/wis/cha saves. Still, it is the main reason I don't like short races for melees (though I do have a gnome + Shattered Flail build, for the wis save factor).
