Never been on one either. Passengers seemed to like it, but not airlines.

With 2 engine planes being allowed to fly across oceans we have ETOPS-240 A-330, ETOPS-330 some B-777 models, ETOPS-370 A-350. Four engines makes a plane more expensive. Maybe A-380 just came too late on the market, maybe some technology jumps were not foreseen or given value.

Unclear (at least to me) is how much of the A-380 learning curve and technological innovation is used in newer planes like the A-350 without being explicitly 'priced' (as in part of the budget) as such.

Emirates asked for a stretched version, then canceled the order. That sounded the death knell. Once the current back log is cleared that will be it.