Unnecessary slang

Problem: I recently was educated about the Philadelphia regional use of the word "jawn" which essentially means anything. (Thank you Urban Dictionary- http://www.urbandictionary.com/define.php?term=jawn). Having grown up in Philly/Philly suburbs, clearly I missed something growing up because I had never heard of this word until a week ago.

First of all, why make up a word that's a substitute for a "thing?" Doesn't "thing" already cover jawn? If it can be used in so many contexts, then what is its utility? 

Second, does jawn wield some sort of awesome factor?  If so, what are jawn's origins? I had spoken to some co-workers who were familiar with the word when they were kids- but that was 30-40 years ago!  Was jawn considered cool a long time ago, and then made a comeback, or was it Philly mainstream for the past 40 years?

Third, if you're going to come up with slang, why would you ever go with "jawn?" It's basically yawn, but a fancy J substitutes for the Y. Although spelling for jawn is not consistent because it is slang, regardless it still sounds pretty lame. 

Solution:  Saying jawn makes me yawn.  Although I am usually a big fan of fun slang, this diction is a bore.  Jawn seems to be an excuse to be lazy about speech that creepily borders on Newspeak from 1984. (http://en.wikipedia.org/wiki/Newspeak) Obviously people can practice First Amendment rights, but jawn is a silly and unnecessary word that should be booted from Philly's vernacular.