Let's face the reality of this situation a bit. Diablo 3 is a damn short game, my first ever playthrough took me less than 7 hours. Each playthrough after that, even less time. Sure the excuse for the lack of content might be the randomization so 'every playthrough is different' but the reality is, it really isn't. The idea is always the same.
'Oh look you ran into x event, kill everything'. That never changes. Blizzard has the base game mechanics. They can do a lot more with it.
Example. We got plenty of different elements; poison, fire, ice, lightning, etc.
Why was there no boss made with the idea, 'hey this boss is weak against x type!' or 'this boss's weakness changes based on it's phase and time.' ?
Hell, why did you guys even both with element-based attacks and weapons at all? They only make a difference if your rolling a barb like mine.
Anyway, my point is, there is a lack of content. Most updates you guys throw out aren't exactly masterful, or require the greatest developer minds on Earth here(simply changing the variables on already written codes for the most part). And Blizzard has also had PLENTY of time to work on new content. At this point, it's just a matter of laziness. Where is PVP? A part of the game that was on the box, but still not within player hands? How about some new in-game content? New dungeons, bosses, etc. With a game where randomization is so heavily played on, you need the content to be there as well. It's not like every enemy and boss has to be related to the main story, especially with this type of game where, quite frankly, no one got the game for the story, and everyone thinks the story is terrible(I think the Belial boss fight was the only point in the game where I thought 'hey that's cool, he CHANGED').