Is there an unneeded hostility towards regular classes in this game?

[Huntington]

I can only form an opinion based on what I've read here. Looking at this objectively, I think a reasonable assumption would that be that if the group asked you to leave based on you being an Arcanist over a Summoner, you would not have simply said "Ok" and left. My opinion, again only gathered by what I have read here, is that you would have engaged them on why you felt Arcanist was fine. One could also come to the conclusion that one end result would have been them removing you from the group via kick. Perhaps they jumped the gun, but I can see tolerance of a Tank / Healer "trolling" being higher since it's much easier to replace a "troll" DPS. Note, this is not to insinuate that you were trolling. However, I can see a point of view where the group could have felt you were trolling.

Depending on what Duty I'm in, I would do the first. Excluding the Hard Mode dungeons like Haukke Manor, Copperbell Mines HM, Pharos Sirius, Extreme Fights, Coil T1 through 5, and whatever else I might be forgetting. Otherwise, I would put forth a reasonable response on why it can work with what we have, or what I have. I've tried to form it as best I can stat wise so that it's only outmatched by SMN by a tad, there will be places where I can recognize that nothing short of my best will be enough, for those I ask to be kicked so I don't incur a penalty and they can get someone else.

As for the Healer and Tank tolerance, it makes sense. In a lot of Instances, if the Tank or a Healer quits, you almost never find a replacement based on hundreds of runs on Shiva, once that happens it's just better to abandon.

[xEscaflownex]

I've tried to form it as best I can stat wise so that it's only outmatched by SMN by a tad

18% + is not a tad, especially over the course of any boss fight, it's tens of thousands of damage.