In particular, Chilton discusses the way that adding a quest-tracker into the game has stifled the need -- and perhaps desire -- for players to explore the world. Personally, I can understand that feeling, because it's obvious that the WoW team puts a huge amount of effort into the gorgeous detail in every zone on Azeroth. In the days before the in-game quest tracker, I refused to download one for my addons, because I enjoyed the necessity of searching high and low for what I needed to find. (I did, however, look up where to find old Mankrik's wife on Thottbott, because that quest, guys. That quest.) In any case, it's an aspect of the game that certainly streamlines efficiency but perhaps at the cost of some of the wonder.
Other design decisions Chilton admits they may look less fondly upon in hindsight is the removal of the completion cap on daily quests, as well as the way the Archaeology profession has functioned. However, the interview isn't all doom and gloom. Pet battles have turned out to be wildly successful, despite some of Blizzard's worries that it might not be the case, so in the end, you win some, you lose some. You can find the full interview at PCGamesN, and make sure to keep your eyes here too, for WoW Insider's up coming Gamescon developer interviews!