Ask most Drupal Commerce 2.x users what their #1 missing feature is, and they’ll say it’s the ability to store and reuse customer information for future purchases, i.e. the “address book”. On Drupal 7, we provided this functionality through the Commerce Addressbook module. For Drupal 8 we felt this functionality was important enough to make it a core feature, and we started working on initial address book patches soon after releasing Commerce 2.0. We didn’t anticipate how wide-reaching implementing our ideal solution would be.