That's just what you are if you're hardcore supporting a pro soccer organization in the US. If by 'hipsters' you're thinking aesthetically, and mean people sporting some particular kind of (probably stereotyped) clothing/fashion style, well, then you're always going to see just what you want to see. And you'll call it what you want to call it. I'm sure I could go to Harrison any old weekend and see plenty of people who look like they just came from the tUnE-yArDs/Das Racist show at McCarran Pool.
This league and this franchise in particular has always attracted and survived upon hipsters-in-spirit - without them there'd be absolutely nothing interesting (or extant) about modern US soccer culture. Because MLS has deliberately steered clear of the old history of the game here, as well as the ethnic influence (past and present). Who else is going to make a sport/club culture here?
Absolutely, but what is "fully accepted" anyway? The Cosmos will attract a lot of hipsters, some soccer-world celebrities to their games, but the city will never embrace them the way they do the Knicks or Rangers. It's just not American culture.
As for Red Bull, as much as we pee on Harrabie for saying it, the brand has a lot to do with the team's "foreignness" to most New Yorkers. Americans are barely used to having a sports team that doesn't follow the generic formula City_Animal Plural. To expect NYC to embrace something that not only deviates from the standard formula, but then introduces an Austrian corporate brand as the name of the team itself...it is way too esoteric for most people's tastes. I'm not complaining, it's absolutely fine by me, but I happen to enjoy the sport. To expect a team of walking billboards playing an unpopular sport to captivate a city with the most other entertainment options in America... is a little far fetched.