A universal remote combined with CEC should make it fool proof for most people. Airplay, for example, will turn on the receiver and start playing and give full control over the volume, so you don't need to mess with a separate remote. Most receivers nowadays stay in stand-by most of the time rather than going completely off.
So the upside and the high price is based on the lack of features? That is new. I use a T-Amp ($39) combined with an Airport Express that duplicates the same lack of features in the Sonos Connect:Amp, I never turn it off, either, so it is always ready to play music. Even if it was off, an idiot could figure it out since it has only one way to use it.
http://www.6moons.com/audioreviews/sonicimpact/t.html
Excess features do not necessarily make something more valuable if they are not wanted, needed, or possibly get in the way. And the Sonos Connect:Amp is not lacking features. It has a very important feature in fact...it is a Sonos component! If you have a Sonos system in your home then that is pretty darn important! The Onkyo AVR, or any AVR for that matter, may have 1,000 features on its spec sheet, but doesn't have that ONE feature I need/want.
Anyhow, I do in fact have multiple Harmony remotes in my household and have used them for at least 7-8 years. Further, I have used T-Amps (Dayton Audio, Lepai, and another brand who's name I cannot remember), all hooked to the exact same speakers, in the same location, that are mounted out on my patio today. And the Sonos Connect:Amp sounds INFINITELY better. It is not even close at any volumes above ambient music. The Dayton Audio amp was good ($100), the Lepai and other were mediocre at best ($25-$50), the Sonos ($500) is excellent. To be fair when I had the speakers connected to the Denon ($600) the sound was excellent too.
Now, imagine if you will, sitting out on a patio, with the Harmony remote and AV receiver about 50 feet away plus 1 story down in the basement. I could put my beer down, get up, walk down to the dark basement, find the remote, turn on the system, select the proper input if I happened to not point at the AV receiver for long enough, walk back out to the patio, pick up my iPhone, open the Denon app, play music.
Or
I could stay seated with my beer in my hand, pick up my iPhone, open the Sonos app, hit play.
I'd urge you to consider multiple use cases, especially if you have family members using the system.
Side note: Yes, there are issues with the Sonos system. It is by no means perfect, and there are dedicated forums filled with people that would like to see added functionality (Bluetooth being #1 on that list, an Aux input being #2, and Airplay being further down the wish lists of most people). But in terms of technical issues, FAR AND AWAY the biggest issues are the home networks, not the Sonos components themselves. Same for AirPlay problems. Most issues can be attributed to the network/router.