Why has Microsoft not allowed browsing for the 360?

Solution 1:

MS now offers an Internet Explorer app for the 360. Contrary to what they say, you don't need a Gold account to download it, but you do need one to successfully use it.

Solution 2:

The product manager for the XBox has addressed this point directly. Quote below, emphasis is mine.

Speaking to Edge, Microsoft's Aaron Greenberg helped explain just why the Xbox will never, ever get its own web browser. According to Greenberg, browsing the web on a television makes for a "poor" experience. Instead, "The real magic," said Greenberg, "is to take those web experiences and optimize them for the living room." He listed the Xbox implementation of Netflix as an example -- the Xbox also has similar Twitter, Last.fm and Facebook apps -- and said that attempting to browse the web on a PS3 is "an absolute nightmare."

Said Greenberg, "No disrespect, there's things I love about the PS3, but that's not one of them." He added that Microsoft wants the Xbox online experience "to be fun and optimized for the living room," and that the company will continue to expand on its applications in order to "get more richness."