You are making way too many assumptions... Remote and mics will work with all devices. Many phones use the same wiring as iDevices (many LG, Nokia, HTC, Samsung for example), this means that the remote and mic will work with those phones as well. The volume control may not work as advertised (for example, on newer Samsungs, the volume up will reroute to the next function while the volume down goes to previous). The center button will work though. It works on Blackberry as well.
NOTE: the function of the center button may only function partially if the manufacturer set it up that way. My LG dumbphone (most smartphones function fine) and older Blackberries (IDK about newer ones) will not have media control with the remote but can answer the phone.
It's not purely iDevice; in fact, remote and mics have been around way before the iPhone, they just weren't used for controlling media and only used to answer the phone. Heck, my mom's old SLVR had a functional remote and mic (through USB mini).
Yes, but you got to understand I don't use my phone for music listening, only my dedicated portable Walkman mp3. So the remote and mic is technically useless for me.