In most dungeons there was a natural progression of bosses. In order to get to the next hardest boss you would have to kill the hard boss in front of you.
The late Wrath model changed this. However in Wrath people still did everything on heroic. It was often seen as a sign of weakness if you didn’t parse your logs or if you didn’t do everything on heroic.
Something is changing in this expansion though. Guilds are killing 10-man bosses once and then never again, specifically Omnitron Defense System, Chimaeron, Nefarian, Twilight Ascendant Council and Al’akir. For whatever reason people are just happy killing each of these once and just doing them every now and then.
It’s kind of a shocking development and largely a failure in design. Generally speaking boss encounters should become easier as you gear up. The incentive of gearing up is that gear will make things easier. If getting gear just increases an unimportant number (DPS/HPS).
Certain encounters may just be too hard or have too many randomness factors to be worth farming consistently. For example heroic Omnitron adds random hard mode combination efforts IE: mass death grip into ooze with lightning conductor. Or on Nefarian getting a tail whip and a crackle together. Given how many times these will occur during progression it kinda makes sense why people don’t farm these.
All the while everyone farms Bastion of Twilight heroic so that they can get their shots in at Sinestra.
It may ultimately be necessary to have more boss encounters like Bastion of Twilight in which you are required to kill them instead of these optional wing dings like Blackwing Descent in future content.
When Blizzard made the first Kael’thas nerf it was because the two guilds that killed it could not/did not want to repeat their kill. It was deemed that farming Kael’thas was simply, not worth it’s time. How is the current Blackwing Descent any different?
TheGameGuru.Me 