Why would I want to install iTunes bloat when I can play, for example, Soundcloud in any browser even mobile browser in the background and screen off?
https://m.soundcloud.com
Because there are millions of i-device users, who are happy in the iTunes ecosystem for their music and other media. There's nothing wrong with this.
Apple would be suicidal however to not allow for windows to be able to play / use / buy using iTunes. Despite how important we think Apple is (they are in many markets), Apple's PC lineup is still a very small player in the desktop OS ecosystem. Microsoft holding roughly 90% of the desktop user space, and Windows 10 has already passed 500 million installations.
making iTunes available for windows is a very important move. And putting it in the Windows Store means that anyone with any version of Win10, including the new Win10s, can use it.