At the risk of repeating myself, so far as I know Media Server is the set of operating system functions which underlies all media operations on the device. So, when you use PowerAmp or GooglePlay to listen to music (on your device or streaming), it is Media Server which actually does the work. When you use TuneIn to stream internet radio, it is Media Server which actually does the work. And so on.
Apps like those mentioned above serve merely as "front ends" which put a pretty user interface on the operating system's media functions.
Taking this info into account, maybe Media Server's battery usage no longer seems inappropriate?