Why does the T-mobile app take up so much space?

I headed over to XDA for instructions on how to get ADB up and running. However, I then realized I couldn't use developer options on my phone as the build number is greyed out. I clicked on the OS about 10 times and a dial appeared, but I'm not sure if this has anything to do with developer mode or if it's just an Easter egg. BTW I asked how to access developer options on XDA and haven't gotten any replies. Is there a workaround?