Altho just my personal experience. I noticed the opposite when I played less attractive classes or specs in wow (or other games) and did well with them.
However, as someone else mentioned that we should think about others.
Perhaps thats a very wrong way of thinking.
Maybe we should be more considerate of others, and think more about ourselves.
As I used to say in WoW: ''I dont care what class or spec you bring, enjoy what you enjoy playing most. Just play your a game on whatever you do bring.''
Which I think is very reasonable since I personally always aimed to bring my SS game myself.(did not always work, but hey they arent proper standards if you can reach them reliably)
Frankly speaking I'd be more alarmed when a tank falls off, or in one attempt a guy uses LB on Bismarck while standing on the island.
You know, the kind thing that actually matters, and that you cant calculate beforehand?
Per defination, numbers are not real.
Unless you define reality itself as theoretical, I suppose.
Damn, I just killed my own argument.
Well nevermind that!
This is solved by having more then a single path of progression. More then a single endgame. Creating anything is complex. And its people that alienate others.
Unless content is literally balanced so that you cannot possible clear it with all of x class as dps, or without having a ''custom'' skill: jobs wont be alienated by the system.
For example in wow fire mages were not a thing in Molten Core. Because most mobs in there were immune to fire damage. That said, it was not like the frost tree was useless, as there were other parts of the game that could be played; not just MC Raid[s]er/[]ing.
This is ofcourse an extreme example, as this customization is more then just a different ability or effect, it tremendously changed the gameplay of the specs to the point where it literally effected where you could go.
Now as far as complexity goes. I will disrespectfully disagree with your statement that designing FFXIV endgame is (relatively) complex. Does it require more time and effort? Yes. Each variable you add increases the time you need to spend calculating and considering. But that doesnt really make it that much more complex.
I came from RO as well. And ill say it again: its people causing grief. I played outlandish or ''standard'' builds all the time.
Im guessing your reason to give RO as an example comes down to personal experiences with this.
Because RO is actually a pretty good example of where customization worked:
-you had vit priests, agi priests, healing priests of various stats. And thats just general builds. Everyone would have their own idea on how much vit, int or str to add to their hunter for example; their own preferences. There was no ''ideal'' build.
VIT vs STR, the example you used is only possible on accessories, and only for tanks since VIT has added value for them.
There is virtually no customization in this game, so im not surprised you grasp for this straw.
Also im sorry you had to grind for hours for great rewards. Currently in HW the crafters have to grind for many hours each week, for virtually no reward.
That's off-topic yes. So is your argument, what does grinding have to do with customization?