I agree that there seems to be what some may call an overabundance of Detroit shirts available. I recently bought my son a shirt that says Another Detroit Shirt, which pretty much sums it up. But I like having lots of options. (Which reminds me, I need to order the Detroitish shirt from Ink Detroit).
Even though the hipsters and travel magazines have picked up on the fact that Detroit is becoming a destination, most people in the rest of the country still don't know. I wear my shirts when I travel; and I'm surprised how often they lead to a conversation with someone who is surprised that Detroit is no longer a "burnt out shell of a city." They're not a symbol of the city's past, they're like the city itself - being reinvented in surprising new ways (Oh, we're making bikes here now? Awesome!).
Thank you Detroit GT, Pure Detroit, Division Street Boutique and the rest of you who keep creating these awesome shirts. I'll keep buying them.