Since the standard U.I is so basic, with the rise of the game more and more mods have appeared with the sole purpose of allowing you, the player, to modify your game in almost any way you desire. Want an MP3 player in game? There is a mod for Silkroad gold. Want to know the gear scores of other players, or know the quickest way to complete a quest? There are mods for that.
As much as it pains me to say it, mostly because I dislike the standard Blizzard U.I., it does not require any mobs to be playable. Yes, you read that correctly I just said that this game is playable just the way you purchase it. If you bring the game home, unpackaged it, install it, and load it up you can begin play with no tweaking needed. However, the standard Blizzard U.I. is very basic, playable, but basic.