Unfortunately, if you have long legs and short arms that's not always the answer. Lately (last 10-20 years) bikes seem to be built with longer top tubes. Therefore, if someone who couldn't reach went to the next size smaller they may experience an uncomfortable amount of saddle-to-bar drop. The problem is compounded by threadless forks having the steerer cut short so it doesn't look goofy on the showroom floor, but sadly greatly limiting how high the bars can go.