To some extent, though. When I'm home, my mother gets extremely frustrated (still!) that there isn't one remote that does everything.
I actually want Apple to do something about this, though I'm not normally in on Apple's philosophy. I propose the following:
1. Any TV channel without content on it goes away. If you only have 3 channels with signal you get no benefit from being able to select 96 channels of white noise.
2. Cable/satellite channels stack on top of the TV channels. It just looks like your TV has more over-the-air channels when you plug in the box.
3. DVD-players and so on are treated as channels (see 3). EXT goes away. A device can be represented by as many channels as it wants, but they're all stacked on top of the TV channels. No special treatment, except perhaps a lower number. A device is turned on when you select a channel associated with it.
4. Any sound systems automatically defer to the settings on the TV. They behave as if they were the TV speakers. No setup. No settings. No knobs to turn. Plug and Play. If a sound system has buttons it's too complicated.
5. DVD/BR players lose all but play/pause, ff/rwd and the nevigational buttons. Why is there a numpad on my DVD remote? I don't even want to know. Just make it go away. Same with the TV remote itself: Everything except on/off, numpad and volume disappears. Remotes are not unified, but everything that can be deferred to the TV remote is deferred to it.
The above isn't completely perfect, but it's kind of obvious.
I'm currently studying but I might be available for hiring or consulting. I obviously compare favorably with whoever is maintaining the status quo.
"Watch TV" - it asks initially, "What input is the TV set to?" "What remote do you use to control the volume?" "What remote to change the channel?"
And from then on, it works. It doesn't cover all on your list, but it has the potential.
For example, I have a TV, a Bluray player, and an AV receiver. I choose the "watch a movie" task, it turns all three on, sets the TV input to the input the AV receiver is plugged into, the AV receiver to the input the Bluray player is plugged into, and then maps the play/stop/ff/rev/etc buttons to the Bluray player and the volume buttons to the AV receiver.
Every button is configurable, all the on screen menu options on the remote are configurable.
An example of something similar: Ubuntu can become as simple as a stone. It would still be too complicated because it doesn't come pre-installed on officially supported PCs. Not third-party-brand-no-ones-heard-about with tentative OS support. I'm talking about an official Ubuntu PC where everything is made to fit with each other. Me and you are OK with patchworks of software and hardware, bugs and weird command line wizardy. Normal people want appliances. Windows PCs are something people treat as horrible appliances, which they've sort of learned to tolerate and work with over a decade or more of training. It's like a fridge with a control panel. Normal people need iOS. Options and customizability are bugs, not features to most people. Sometimes some (but not most) people want more than just an appliance, but they still want the minimal complexity possible given their requirements. Buying extra remotes or installing another OS is really not what they want.
Downvoters: I dragged desktop Linux into this because I'm excited about Linux and because it's hopeless as a consumer product.
Logitech isn't really the company to do this. Apple would be great. Their brand is perfect for this. Apple's brand is, as far as I've gathered, "open your wallet and we'll make your tech easy to use, trouble-free, beautiful and sure to impress your friends". Logitech is "that keyboard/mice company". Would you buy a TV and HiFi from Logitech?
Another glaring problem is how it decides to carp about low battery levels right in the middle of what you're doing. When this happens, it ignores your input until you acknowledge the low battery warning. After you acknowledge, it completely forgets what you were in the middle of doing. As if that weren't all bad enough, the battery warning can come back at any time after you dismissed the last one, including immediately, one second later, etc.
I find myself using the individual remotes more and more often in the past few years. They are stateless, have excellent battery life, and are incapable of measuring their battery levels. They don't have any of the Harmony's bad habits.
When I was 4 we had a cable box and a TV. I could obviously see that the cable box had its own volume and its video output was its own thing that only went to one channel on the TV itself, because it was what turned the cable wire coming in into a signal, which it put on its output cable wire directed to only one channel, channel 3 or 4, and that that applied to its volume as well. Nobody explained it to me, I could just tell by looking at it. I wasn't a "geek" or a "techno-fetishist." I don't think anyone of any age who thinks about it for more than one second finds this a difficult question, hopefully.
50% of all people are dumber than average.
More importantly, though, is that the current arrangement is inelegant.