This won't be as long as the other one, I promise.
First of all, I was entirely correct in that, had Blizzard simply let me start playing on a higher difficulty level, I would have enjoyed the game far more.
Perhaps if I had stepped away from the game for a long while and come back and played it on the so-called Nightmare difficulty, I could have gotten a new sense of the story. Much like re-reading a book after many years, when you have forgotten many of the details. However, I wasn't about to do that. It's a new game and I'm gonna play it now.
I say again that the game and story are inextricably linked only on the first playthrough. On subsequent 'runs' nobody cares about the story. They don't stop and listen to the dialogue, and they probably don't even pause to watch the cinematic. Later playthroughs are not about atmosphere, or appreciating the finer points of the game - they are about loot and experience. The faster I can click on the hostile little bundles of pixels, the faster I can gather up both.
I covered a bit of how even the loot system feels cheapened in Diablo III, and I won't rehash the topic. Suffice to say that the blow to the story of Diablo III - which, while actually the least well-written of the three games, is still pretty entertaining - is almost unforgivable. I would have enjoyed it far, FAR more if I had merely been allowed to pick a higher difficulty setting from the beginning.
I know there are reasons for their choice. As a game designer myself I can see some of the logic behind it, but in my own humble, not-earning-billions-with-my-games opinion, I think they did it poorly.
Also, the permanent Battle.net connectivity requirement is a horrible decision as well. I'm basically writing this because I can't log in to Battle.net in order to play the game completely solo - because, despite its flaws it is still a decent game (and moreover, one I sunk $60 to pay for) and I'd rather be playing it than complaining about it.