I just listed all the reasons, lol, you don't want to sit through that again do you, lol...
I agree, you can get an avr to sound fine, but I prefer a separate system... I HATE shuffling around and changing settings to listen to music, plus I could NEVER get time in the HT to listen to music, that would take an act of god between my wife and kids, that room is siempre ocupado ....
You can not argue- that you prefer to go into your HT and listen to music vs a designated area with a designated system? Come on'.... Walk in my front parlor {no tv in there}, hit 1 button and music is playing!!!!!! vs go to ht, turn on the avr turn off the tv, switch it to music pure direct mode turn on your audio device, or what ever.... I like my way... And it sounds very good. Try A B comparison of a simple integrated amp like the topping tp60 and any mid level AVR ($400ish), I have done this and prefer the integrated amp for music... Now with movies its obviously not that simple, you need whatever dolby decoding and surround modes, and room correction, ect... music is easy, set the speakers in front of you left and right, and press play, adjust volume to suit and enjoy...
Now if space or budget are issues, sure use your avr for music why the heck not....