Kaplan was quick to note that Warcraft was far from perfect, and he wanted to highlight some of his own mistakes inside of the design.
The first mistake was the idea of the "Christmas tree effect," otherwise known as having so many quests in a quest hub that the minimap lights up with exclamation points like a Christmas tree. While players enjoy this, Kaplan wanted to say that the developer loses call control over the player at these points, as the player will not read any quest text in their clicking frenzy. There's no control over what quest leads into what or which order the player will do the quests in.
The second was the internet adage of "too long, didn't read." Quest designers don't need to write a book to get their point across with the quests. He brought up that video games had a type of "medium envy," where sometimes they get too preachy with their topics. Games should be fun first, story second.
Mystery also falls in this category. The story can provide mystery, but the quest log should never have any mystery to it. The quest log should always point where to go and what to do, but the overall story of those quests may provide some solution to some mystery.
Also avoid poorly placed quest chains, like the Chains of Myzrael questline in Arathi Highlands. The Myzrael line was hard to find, ended up spanning 14 levels, and ended with killing an elite mob that was level 44. This quest line was a "brick wall" according to Kaplan, because most players never stuck with it.
It's good to have quest chains that span content, but quest chains like this break down trust the player has with the developer. When the player runs into a chain that he can't finish with a monster he can't kill, the player loses trust in the developer's sense of guiding them to fun.
He also emphasized to avoid inserting "gimmick quests." His example here was part of the Oculus dungeon where players ride on dragons. These types of quests center around doing something the client may not be able to properly handle. Warcraft was not designed to accommodate vehicles. When developers resort to putting in parts of the game that center around a gimmick, it can detract from the fun of the rest of the game.
The horror of collection quests
Kaplan's speech ended with an analysis of why people hate collection quests so much, and a few tips on how to make collection quests into a better experience.
His problems with the quests stemmed from three areas -- dense creature population, too few of a creature to kill, and having a wide variety of items required for the quest. Having a dense creature population can put off people, especially when there's a lack of the monster required for the quest. If someone has to kill four lions for every one raptor required for the quest, then there's a problem.
His other point was that collection quests shouldn't require an insane amount of items. To everyone's amusement, he brought up the Green Hills of Stranglethorn quest chain (a chain he wrote) as the exact thing a designer should never do. Collection quests should be an easily obtainable number of items, and not such a long grind fest with the hope that your required item might drop.
Lastly, never have the player question why they're collecting the item required -- it should be clear from the onset. Kaplan brought up the infamous gnoll paw collecting quests, in which gnolls may or may not drop paws upon death, where obviously a gnoll has four paws and not a number between 0 and 1 (which everyone applauded at loudly). Quests should make sense and not become a gimmick in their own right. This causes the player to once again, lose trust.
Most of these points that Kaplan has brought up pertain to Warcraft, but can easily be applied to any game on the market. With all of this in mind, perhaps we'll get to see some better design in our MMOs from other developers, now that we're all on the same page... of the Green Hills of Stranglethorn.