Wolfman - I’m with you! I see we’re a distinct minority here, but I’m with you! I wear jeans and a T-shirt all the time, with job interviews being the sole exception.
A tie serves no purpose other than to restrict blood flow to the brain. The last time I wore a “noose” was to a job interview where I was shooting for a $70-$80K/year job. I have my principles, but I have my price, too.
I don’t dress up for a couple of reasons. One is a matter of comfort, the other, a matter of principle. I’m just not comfortable in dress clothes/shoes/etc., and I’m not willing to compromise my comfort to conform to some arbitrary social norm, no matter how dearly held that norm may be to those around me. Usually, this isn’t an issue. I don’t tend to go to formal events, and when I do, I just wear the same ol’ black-jeans-and-a-T-shirt I would wear anywhere else. I refuse to go to any restaurant with a dress code more stringent than, “no shirt, no shoes, no service.”
I work for a very small company, and two of the three major shareholders/owners feel exactly the same way I do about dress codes, and the third tolerates the rest of us quite well. For a while we were merged with another company whose CEO tried to impose a dress code. We all balked and he caved in. It helps that I’m a computer geek - we’re known for our disdain for dress codes, and it’s largely tolerated (at least in any company I’d work for). Of course, I now telecommute, so I can work naked if I want. Heh…
My girlfriend is very much into the whole dress-up thing. She has, like, a zillion pairs of shoes. I have one pair of shoes. She just bought a lot of 60 “scrunchies” on eBay and insists she now has to have an outfit to match every one. She thinks my attitudes are blasphemous, but she tolerates them quite well. She was a little freaked that I attended my sister’s wedding dressed in my usual garb, but she got over it. My sister feels the same way I do about clothing, so I wasn’t offending her, and anyone else there who had a problem with it was cordially invited to kiss my hairy white ass. 
Like I said, comfort is my primary motivator for how I look. I do some things people consider normal and good purely for reasons of comfort. I never wear dirty clothes - they feel nasty against my skin and often smell. I keep my hair quite short and neat because it dries quickly and doesn’t get in my way. I keep my face clean-shaven because I can’t stand facial hair. On the whole I’m a very presentable guy, but you’re not going to catch me wearing a suit any time soon.
One day I hope to go to law school and become a lawyer. Given how much money I can make, I’ll deal with having to wear a suit. Until then, it’s black jeans or denim shorts and a T-shirt for me.