256kbps is not really audibly transparent, I can pick it out everytime in foobar abx tests. Transcoding lossy encodes isn't as simple as you make it sound. Depending on how it's done it can sound pretty terrible (and almost always does). As for AAC support, I don't know, I don't use it.
Personally I like to know what I'm working with and how it works, and I like to be able to configure it to my liking, all of this without overspending. I also want choices in which apps I want to use. Also you don't really have to spend much time making sure products/apps play nice, depending on the level of freedom you want. A PC can integrate perfectly with any device, android, windows phone, whatever. You can use any remote control app such as VNC for instant access through your phone (or any tablet, laptop, etc) to your complete server. You have literally hundreds of choices for music player, even more so for playlist control, video playback, etc etc. It's just a matter of picking the one you like best, rather than going with whatever you're given without being able to configure it extensively the way you want it. And all this without wasting thousands of dollars on a pretty design and inferior/slower hardware.
I have my TV plugged into my PC, which itself is remote controlled via VNC by my android phone. Not only can I access it anywhere in my house (neighborhood, in fact), I can also access it from across the planet if I need to, and control absolutely everything