The world of home a/v receivers is a wonderfully rich horrible hateful bad evil dumb broken idiotic backwards dumbass UX.

• The UI of all receivers is, apparently, like dog barf. And no I don't really want to have to dedicate my cell phone to fixing their UI problems so "having an app" doesn't satisfy me.
• Simple things like remembering that I had "night mode" audio compression on.
• Advanced features like auto diagnostics that show me what part of the audio/video path is failing. Both in terms of standard crap like HDMI handshake failures, and in terms of long-term out-of-warranty internal hardware failure.
• The front panel is just pathetic. It should be a full on bitmapped graphic display.
• Physically I haven't really seen a receiver that isn't sorta just gross or lame. They are neither something that is cool enough from a technonerd perspective, nor attractive enough from a tasteful home decor perspective.
• The rear panel hookups are always a nightmare once you've ever installed things. Just physically being able to get back and change things.
• Rear panels are often not designed well e.g. on Denons it looks like often the component/composite video input is not physically lined up with the matching audio. So that's a bloody nightmare if you are hanging over the back of the equipment trying to read the labels upside down.
• Anybody who uses an intense blue LED (this includes things like Panasonic M43 cameras' "iA" button) deserves to be taken out and shot. If you ask me.
• The fundamental problem in my mind is that a lot of receiver UX fails to make the abstractions make sense. Instead of manually digging through menus and manually mapping inputs and outputs, the UI should more automatically help map things; should also show things visually e.g. (strawperson idea) show a vertically scrolling list of inputs on the left, and a vertically scrolling list of outputs on the right and let you match them up.