Who said they were perfect? No one but Hashem is perfect. And it is not coddling a grown woman or man to refrain from hurting them by telling them how much they need to work on themselves to improve themselves. What right does anyone have to do that? That may be true for SOME adults single or not, but to imply that is why so many if not most are still single is wrong. I know a lovely young woman about to turn 29. She is pretty, has a warm and lovely personality, is a great conversationalist, witty, great cook and baker, not a size 2-4, but not fat, either,and she is set up with one inappropriate shidduch after another. One was borderline developmentally disabled. She does not have to “work” on herself and change her outlook on what she wants. She wants an ehrliche, non-Yeshivish, modern but machmir frum, down-to-earth guy, who is warm and loving, has a spirit of fun and humor as well as responsibility, and wants to raise a family in a Torah environment that also includes the secular world. I would venture a guess that many of our singles want the same thing. Instead, she meets guys who are DECIDEDLY Yeshivish (and after she spoke to one shadchan about what she is looking for, he set her up with a guy who at 32 is still in Yeshivah, with no parnassah). Please don’t tell me she needs to adjust her thinking or work on herself. She is a terrific young woman, and everyone who knows her adores her, but they just don’t know guys for her.
There may be some young people who could benefit from what you are saying, but I doubt that this is true for most of them. And it is unfair to say that it is. If they refused to go out with a dark-haired girl because they only want a blonde, or a guy who is 5’7″ because they want 6’2″, then you would be right.