I think T-shirts are fine when I'm working under my car, playing a game of footie in the park, etc. But if I'm going out somewhere, yeah -- I don't want to look like I just got released from prison. Part of that is self-respect, and part of that is showing respect to the people around you who have to look at you.
For example, I don't get the mouth-breathers who walk into nice restaurants with a hot woman wearing ripped jeans and a T-shirt. There's a time in life where it's ok to socially dress like a 8-year-old school boy. But there's a time in life where you kind of act like an adult, or at least attempt to show the dignity of one.
If I'm going to go out somewhere nice, I would prefer to look the part. And if that means spending $100-200 on a decent get up, I sure as hell would rather by a well-designed shirt than a faux upgrade to something shot out of a cannon into the crowd as giveaways at sporting events.