In an item farming game like Diablo 3 efficiency is king. Players want to find good items and lots of gold. That means killing the most monsters and bosses in the shortest amount of time. This creates the trifecta of DPS, movement speed, and survivability as the most desired qualities in a character. After all, when you are putting thousands of hours into gearing up a character, even small increases in efficiency can result in massive time savings in the long run.
Of the three, DPS is probably the most obvious. The only way to kill monsters is to kill them with your character’s damaging attacks. More DPS will of course speed that up. You can see the effects of this when looking at both the most popular skills and the most popular runes. The most popular skills and runes are always the ones that do the most damage. The Diablo 3 designers could improve this area by making all runes do the same baseline damage. Each rune could then have a different utility based on the players preference. That would at least add some rune variety. I do not know an easy way to balance the base skills though.
Movement speed is a little harder to see, but it clearly has a big draw. Some of the most popular legendary items have movement speed bonuses. Every popular character build includes a skill that boosts movement speed. This is because there is always a little bit of running from monster pack to monster pack.
This is especially true when your character is really well geared. You no longer care about picking up magical and rare drops. The only monsters you want to kill are the elite monster packs. There’s only a few on each little map in the game. Every veteran player wants high movement speed to run through the map as fast as possible picking off just the elites and mostly ignoring everything else.
The Diablo 3 designers could improve this area by balancing out movement speed between classes. All classes can get to the +25% movement speed cap from gear, but most skills can go above this cap. The Barbarian has it easy with the low cost, spammable Sprint skill, not to mention infinite Wrath of the Berserker. The Demon Hunter have it pretty tough with the relatively high cost Vault that also has a cooldown. The Barbarian happens to be the more popular farming class. Imagine that.
Survivability is important because dying causes a loss of around 30 seconds. In the long run, that makes a big difference. The Barbarian has low cost, survivability skill buffs that last a short time. The Demon Hunter only having separate survivability skills must directly hinder their DPS to use them. Also the moving around and dodging that playing a Demon Hunter requires is just plain more work than tanking everything with a Barbarian.
Survivability would be much harder for the designers to balance. The Demon Hunter archetype is more of a class cannon. They are supposed to do high damage, but have low survivability. Perhaps the designers could increase Demon Hunter DPS above the other classes, but that causes its own set of problems. Because DPS equals more drops found, some players might feel forced to play a class they don’t like just because it has higher DPS. So for survivability, I really don’t know what they could do to fix the problems.
In hindsight these things are easy to see. It probably wasn’t so easy for the Diablo 3 designers to see when no one was playing at endgame yet. They had some people doing that internally, but it required a lot of players putting solid hours into the game for these flaws to become apparent. I hope the Diablo 3 designers will at least balance DPS and movement speed between the classes, skills, and runes. Survivability may not be possible to balance, but at least the other two can be balanced.
Of course I have avoided the other big problem in Diablo 3, itemization. This topic gets all the attention these days, so I will not write anything on it. The Diablo 3 team has already said they are hard at work on this. What they haven’t talked about as much are the problems that efficiency causes I listed above. The itemization patch will probably happen a few months before the first expansion. Hopefully in an expansion, they can fix the DPS and movement speed balance.