The reason why gold was made so you just had to walk over it was so console gamers could loot it. This concept could easily carry over to loot.
The reason the quests make you walk in a linear closed circuit as opposed to big open worlds, is to keep your buds next to you on the same screen.
The reason for no skill points or complicated number crunching? To make console players happy.
The reason you have 4-5 skills on your bar at once? Very easy to use an Xbox/PS3 controller to use skills.
The reason no runes/complicated item mechanics exist? It wouldn't be fun for console gamers and would be too complicated for the use of a controller.
The reason you can't host a named game? Auto join for console users.
The reason for achievements in game? It's popular among console gamers.
The reason for passive skills? Perks like Call of Duty uses. Everyone unlocks perks and uses their favorite ones.
PC gamers are just beta testing for the console release so it wont be full of bugs. That's how Blizzard intends to make the real money.
Also explains why the game doesn't have VoIP for PC gamer chat.
Diablo 3 is the modern Call of Duty of ARPG's.