Sega would've cut out part of the game to include it if they wanted to focus on flawed heroes. They didn't.
The game really doesn't focus on any heroes (other than Nei and Rolf, of course). We can't say, just from the game, if most of them are flawed or not.
And don't forget, Sega did make 8 more games just focused on the heroes. Those games would be better criteria to judge their character by.
Losing someone you care about isn't a character flaw; it's a trait of a value-driven person. Someone who doesn't take a love interest's death hard is a psychopath. That's a character flaw!
He knew her for, at most, an hour before she died. That's not long enough for such a bond to form in a healthy relationship. It's less love and more fixation.
but the point is that story is not driven by them. In FF, the character flaws overwhelm the storyline.
Yes, you're quite right on that.