On the topic of "perfectly pretty characters"...
I feel like the reasons mentioned are fairly accurate... but in my opinion it's probably due to "protagonist syndrome".
As writers, people will be proud and excited to act out their characters actions in written word. A lot of the time, especially with newer Role players, people will tend to want their character to be someone of major importance to the story and subconsciously when building their characters they will try and include certain aspects that will make them more appealing as a central character. This can sometimes bleed into personality, which leads to "Mary-sues and Gary-stues", but the more common example is found in the appearance section.
Ninety percent of the time in media of all forms the main character is good-looking, attractive and likable. This is because these qualities make us like the stories protagonist more and root for them to be victorious, "quirky" aspects like physical imperfections and weight can be added to side characters and villains to give them their own charm. So long as they don't take away from the protagonist.
As people we will always be influenced by other people, we know that the populace likes better looking characters most of the time and without even thinking on it deeply we often want our own characters to match these standards. As we get better at RP we begin to see that every story needs characters whom are more imperfect in personality AND appearance (it makes for better character development and more potential for interesting sub-plots), though even then we still tend to make "pretty and perfect" looking characters from time to time.
Now, I'm not saying that making beautiful characters is a bad thing at all, nor am I saying it's a primarily rookie mistake. I'm just saying that it's a common thing and it tends to be more frequent with newer players.
At the end of the day, in writing games such as these, appearance is only one small factor in the larger scheme of things and I find that other aspects are much much more important. Still, it's fun to talk about and improving on these tropes is a way to improve all of our skill in the long run.
Once again though, this is just my two cents on the issue.
Hello I'm not entirely new to RP's but I am new to PC and just want to say hi and hope to enjoy RPing with a lot of you. Sorry if this sounds like an introduction but might as well start off with a hello right? :)
And hello there Haunter! Seems you've managed to make your way to the RP trouble without any trouble... welcome to the hub of interactive writing games here on PC! I anticipate many great RPs in our futures!