I don't mind wearing a suit I spent all of highschool wearing dress clothes. I'm 100% comfortable in a well-fitting suit. I bet many people are not. You can't just put on your suit for one day and be comfortable in it for the job interview. You have to know how to wear a suit and still carry yourself well. So yes the people complaining about suits probably wore casual clothes their whole lives and aren't comfortable in a suit and blow their interview with bad posture and such.
I could be comfortable in a suit. I've worn the Army equivalent, as well as a sport coat, just fine.
I have a slight problem that I bet does translate to appearing uncomfortable, though I take great lengths to pump myself up with enough artificial confidence to try and minimize the issue: I'm deformed.
Call it a "cereal bowl chest", a "concave chest", a "hole", whatever... my lower ribs are quite concave in the middle, and seemingly stick out further at the outer edges. It seems to push my diaphragm lower and in general makes the part of my chest/upper body that is furthest from my spine the bottom edges of some rib bones, and not the pectoral muscles. I've been working on my pecs (all over, really) to try and build up and cover this nonsense, but until that day arrives years from now, I cannot get a single tailored jacket to fit right. Hell, even slim-fitting dress shirts and whatnot don't fit right.
I'd rather not look awkward and uncomfortable in a suit, when I'm clearly not physically capable of anything else at this time. I do what I can to find the right colors and fits to minimize the appearance of my deformity, because I know it probably is causing acceptance issues.
I mean, when all of you pro-suit hiring managers and whatnot utter these opinions about looking well-groomed and confident and having clothing that fits right... you see my dilemma. There is no shirt, no jacket, that literally fits me right. The way material falls, it just ain't happening. I can get close, and I take great lengths to get there...
I just know some of you are going to be ignorant and take a first look, see my shirts fit me oddly compared to almost everybody else, and just go with your first assumption: I'm lazy, don't take the time to get dressed correctly, don't take the time to find the right fits or get things tailored... etc etc etc.
I sincerely hope I haven't lost out of a job for that reason, but I can't do a damn thing except appear confident. For the most part, I am confident and feel confident in an interview, and ensure I am presenting that physical posture... but I can't do anything except get as close to a good fit as possible, and ensure everything is at least coordinated correctly. Otherwise, hopefully they look past the fact that something seems weird about the way shirts fit me.
I have no intention of buying a suit at this point in time, mainly for that reason. Also, I have every intention of building enough muscle that getting something tailored now would be a waste, especially since it wouldn't fit right one way or the other.
I also don't suspect I can ever truly overcome the skeletal shape, not without being a barrel-chested mass of muscle, and I don't intent to go that far.