That may be so Nathan, and I see your point of view, (and I've been playing DW since Tony first came up with his idea in Apoc D&D) but Sage and Adam are trying to prodce a published game, that already 'mimics' (for want of a better term) large parts of the AW text - Guide to moves, playbooks, guide to advanced moves (mistake and correction), The GM Agenda, principles and Moves, Fronts and Dangers, Sage's latest suggestion in this thread for injuries (straight from AW disabilities) etc..
So why not a section on 'Advanced Delving'? The concept of Love letters is a brilliant way for the GM to tie the characters in to the fiction with a custom move between sessions, and so, so worthy of inclusion into the ruleset. In fact a whole section on writing custom moves is already included! Why not include love letters? Ensuring that there are examples specific to DW and the ways you can use these tools in a fantasical, heroic setting (instead of a post-apocalyptic one) I would have thought is vital.
Many folks will pick up Dungeon World having never played AW, they just want to try the cool indie dungeon delving game they have heard about. The rules they buy later this year may be the only *World game they have read. I support and encourage Sage and Adam to have their own game, not just a supplement to AW that you need to 'port' the rules you need from the 'advanced fuckery section'.