I know you were trying to be funny, but you have inadvertently brought up an important point. Just as people judge you by the way you dress, they also judge you by the way you write and speak. Occasional errors are excusable, but consistent misuse of the language damages hampers your ability to communicate with others.
A colleague of mine had a teaching assistant whose e-mail to the students was always full of errors in spelling, punctuation, and grammar. For instance, he would not bother to capitalize the first word of a sentence or put a period at the end of a sentence. He steadfastly maintained that such things are unimportant -- the reader could figure out what he meant.
However, it is not true that the reader can always figure out what was meant. Nor should he have to. Communication is difficult enough; frequent errors tend to draw attention to themselves at the expense of the message. The writer who insists that such errors do not matter can reasonably be accused of showing contempt for his reader.
Likewise with clothing. One of the purposes of clothing is to communicate. Those who dress inappropriately for the occasion tend to draw draw attention to themselves. In some cases, they can reasonably be accused of showing contempt for others who are present.
"One of the purposes of clothing is to communicate."
HUH? You know that never occurred to me. Maybe it's because I communicate with my words and deeds, not with my clothes. I've never thought that my clothes could do the "talking" for me. My husband would probably like it if they did! Sure be alot quieter around here. LOL
Ok, I know you're quite serious so I apologize for my laughing about that statement. Maybe I'm just too much of a simple lady. I know there are women (and men) who dress to impress, but you know what? It doesn't impress me. I like dressing up as much as the next person, but I certainly wouldn't want to be judged by what I'm wearing. Heck, I could wear a formal gown and some hoity-toit would judge me on the style I chose or the color and come away believing that I was somehow not as good as they are.
I remember some of the snooty women in our church. I swear they acted as if the biggest thrill they got out of Sunday service was gossiping about what some other folks were wearing. Shameful.
As for the other part of your post, it's mixing apples & oranges. Yes, if one wants others to understand what they are "saying" or "writing", punctuation, and speaking skills are important. If someone chooses to not use punctuation, etc., then they are choosing to make it difficult to be understood.