I don't really know if the premise of your commentary really holds. I don't think I've played many RPGs where the heroes are perfect. They all have flaws in one way or another, even if that flaw isn't bipolar disorder, or being out of shape.
I think the problem with certain flaws, is that they can be so pronounced that they end up dictating what sort of story you can tell. It really depends on what kind of story you want to tell, or what sort of game-play you want to design, and you should usually jot that down before you end up designing the particulars of your characters, unless of course, you want to make a character driven narrative and design everything around that.
It's also worth mentioning that "relatability" is usually an important factor if you want a story to hit a wide, or big audience.
Telling a story about a bipolar person for instance, is difficult, not only because it would require you to be well-versed on bipolar disorder in order to tell that story in the way that it deserves, but because many people might find it hard to relate to regardless because they have no experience with it.
(I for instance, have a close friend who's life was nearly ruined by a girl with a bipolar. He developed depression and was forcefully admitted to a psyche-ward for observation after attempting to kill himself, so I would probably not feel very comfortable playing a game that didn't tactfully address the reality of mental and personality disorders.)
Similarly, many people play games as a kind of escapism. A lot of people pretend to be above that - usually, they just desire a different kind of escapism and aren't aware of what they're doing.
I get to see the unattractive, mundane, depressive and harsh sides of reality every day, just by walking outside, or on my extra-job.
In playing games, I want to experience a good story and game-play, of course, but often I also want to the story and game-play to reflect things I don't get to see or do every day.
Ridiculously visually appealing characters, supernatural abilities and fantastical vistas of physically impossible architecture and nature, all appeal viscerally to something deep within most people. It can take you out on a cloud, and drain you of the emotional heaviness that reality sometimes inspires. There is something profound about that kind of art as well.
I like to think of games, in terms of an analogy, as pending on a spectrum between Rococo and Realism, in terms of the spirit of their design.
(games ranging from Super Mario to Bayonetta, being the Rococo, and games like Gone Home and the likes as being Realism).
There's room for both, but they speak to two completely different set of emotions and values, and due to the nature and history of gaming, I think you'll find that more gamers than not (going by sales numbers and general sentiments online), lean towards to "Rococo gaming" , rather than the heavier and more moody "Realism Games".
(Note that I am not using Realism here as analogy to realistic games. This analogy is about overall spirit and style, rather than whether the game is realistic or not. I'd put games like Gears of War under Rococo in this category, because the spirit of the game is more in line with games like Bayonetta, with the ridiculously over-dramatic set-pieces, and power-fantasy theme, than with games from the other side of the spectrum).
