If I'm going to be totally honest, both as a GM and a player, I consider the character sheet as a sort of job application. The GM reads it, stashes it away, and you hopefully never need to look at it again. The only time I look at a character sheet once an RP begins is to figure out how you spell a character's name. I tend to write everything into the story regardless if it appeared on my sheet or not.

I think the reason why people are so specific with outfit descriptions is because they don't like to see slip ups. If my character is wearing a winter coat, you can't observe her cleavage until she hangs it on the rack, because she's got a tube top on under there. Keeping the uniform consistent isn't realistic, but it does make it easier to write about the character. If the RP is really moving, I might not remember if your character is wearing their long sleeve coat or just has their t-shirt. When your character slips and almost falls off the edge, she's going to grab your hand, not your sleeve, if you're wearing your t-shirt. Also, most knights don't have more than one or two different sets of identical battle armor. 

I think most roleplayers like the idea of having a trusty weapon that becomes the character's identity. Drow are all just dark elves with white hair. But if you give one of them Twinkle and Icing Death, he becomes Drizzit!

Personality is, in my humble opinion, one of the most silly things to ask for. There simply is no correct way to portray a character's personality because there's always an exception to the rules. Bill tends to fly off the handle, but he's more reserved around Amy. But he'll snap at Amy any time she brings up Joshua. It's hard to do, and I always feel like i'm going against my character sheet when I'm asked to fill out their personality.

Bio is the one thing that I'm pretty sure I never fill out right. Like, how much do you really say? I plan on uncovering everything as the RP goes on, but like, I'd like to keep a few secrets ya know? I feel bio really should include stuff to give you an idea of how the character thinks and behaves. In fact, i think a bio should really be there to replace personality. Just write about some events that define the character.

I suppose this is why all GMs use slightly different character sheets. They are all looking for different kind of information about your characters.

Worthy of note, I joined an RP that didn't require any character sheets. Yes, it was a sandbox RP and we were all close friends, but it's actually turning out pretty good. What's holding everyone up are everyone's post rates. Nobody's complaining about god modders or how character X isn't using magic the right way. I'm not saying it works for all role plays, but it just goes to show you that sometimes you don't need all that information.

In closing: I feel that if your players aren't filling out your character sheets the right way, you haven't made it clear what sort of information you want from your participants. Some of these characters are opening their eyes for the first time, and I suspect even the players don't know exactly how they are going to behave in all situations.