The phone book screen has been made much taller so more entries can be seen on the screen at the same time, as well as making more groupings.
The current phone book screen has 8 tabs and up to 24 lines are shown at any one time. With the new version there is 12 tabs, and each tab can show up to 37 lines at a time.
More tabs means most tabs cover 2 letters instead of 3 at the moment. Only the last 2 tabs cover 3 letters.
The original phone book was created back in the day when we had smaller screens, so the phone book has to fit in a 640×480 screen resolution. Now that we have more space, we might as well use it.