tl;dr The plane is too big (600 seats) and airlines are concerned that it is/would be too hard to fill all the seats. I was hoping for some interesting manufacturing quirks or something :/
I think it's still interesting, because (20 years ago) Airbus and Boeing made two very different bets on what air travel would look like in the future. Boeing thought it would be mostly P2P and built the 787; Airbus thought it would be hub-and-spoke and so built the A380. It's going to take a decade or more for this to play out, but this might be the first sign that Boeing was right and Airbus was wrong.
Of course Boeing also bet that they could bust their union* to goose profits (jury is still out on that) and outsource manufacturing (massive failure). The 787 was almost a disaster because of it. They had to go buy out a number of their suppliers and bring other work back in-house.
Just about the only bright spot is their partnership with Japanese companies. That's why Japanese airlines massively prefer Boeing planes and is a strategic effort on Boeing's part. (It's also why Japan took the battery failures so seriously: the batteries were made in Japan). If I had to guess, this is also a strategy Apple uses and part of the reason they buy Sony camera sensors and helped Foxconn invest in Sharp's display production.
* This one irks me because they're in an effective dualopoly with Airbus and profitable. It isn't a Detroit situation where the union was imposing massive inefficiencies on the business. It's purely an attempt to screw the lower-level employees. People wonder why incomes have been stagnant for so long... The richer you are the more money permanently joins the capital class vs circulating in the economy as spending. The more money accumulates at the top, the more excess capital and weak spending you'll have.