Maybe teenage girls are putting more money in Apple's pockets than the "MANLY STRAPPING GUYS".
They do. They also buy more clothes, so the clothing industry concentrates on females. And I even have problems to find "normal" Mangas directed at a male audience, all they have is either Ecchi or Kawaii. It's hard to be in the minority of customers still looking for some good science-fiction.
What does this have to do with whether iTunes Radio is a standalone app or not?
From the users point of view, a standalone app is merely an appearance change. Just one more icon you have to look at, when browsing your phone, not only when you are inside the app. From a developers point of view, a standalone app allows more frequent updates, independently from iOS updates. When you want to talk about that aspect of being a standalone app, please do! I'm talking about the look of it.
Well T-Mobile doesn't seem to think so and you might do yourself a service by expanding your vision on what's considered "girly".
T-Mobile is a marketing brand with the need to scream for attention against the competition. One of the biggest benefits of Apple being an integrated hardware and software company is, that not everything is a separate profit center. Many parts and functions of the system can spare to draw attention on themselves and just work invisibly and transparent to the user.
FAINTLY EXAMPLE: Open up a self-build PC and everything inside it shines in bright colors. The graphics card looks like a technological marvel just to proof to you, that it was right to choose this vendor over another. Open up a Mac and everting is black including the memory. You might not even find the graphics chip.
The same principle is true for software. iOS doesn't need to advertise for itself, you can't buy it separately anyway. So the system can be deemphasized, diverting all the user attention from the application chrome to the content. When I open a music app, I want all the controls to be gray, only the album art should have color. Not before a control is active (music is playing, shuffle mode is activated), it should get a systemwide (or app-specific) highlight color. Just like things work in OS X.
I disapprove the meaningless new use of color in iOS 7 in general. It makes the iPhone more like a toy and less like a tool. That pink icon just was a reminder for me. Some people dislike the use of skeuomorphism, where it doesn't need to be. And I don't like the use of color, where it does not need to be.