I agree with BARomero that the sentiment is nice, but, for me, the parable lacks a little, and comes across a little cheesy.
Although the mantra “Show, don’t tell” is overused when talking about fiction writing, I believe it applies here. Rather than being told he was homeless, weirdo, or begger, I would have loved for you to have described it to me.
Krulltar hit my point on the head. the last paragraph is all preaching and no showing. Sometimes it’s better to leave the meaning a little more unsaid. Also, you have a lot of run-on sentences (“comma splices”) that could use some attention. It has a nice overall feel to it—just needs some polish.
Just a quick side note: this reminded me of a story I read some 20 years ago in college in a book called “Sudden Fiction International”. The story was called “There’s a Man in the Habit of Hitting Me on the Head with an Umbrella” by Fernando Sorrentino You can find it at: http://www.eastoftheweb.com/short-stories/UBooks/TherMan.shtml
I like how just by sitting down next to him, the main character becomes just another person that is ignored. I was a little confused on the “more empty space than fabric” line but it ties in with the end and I like it regardless.
I think the idea was solid, and the concept of his jacket, your most powerful image, should be the central theme of the story so you don’t have to spell it out at the end. In fact, you could have it so the protagonist realizes that about his jacket near the end, so the subtext is that he realized this truth about life, too. Good work!