What’s the logic behind not having a turn off button?

If you are using all devices daily, leaving them on all the time may have a small energy use/cost, but eliminating that will be offset by reduced service life caused to the units by a daily power on/off. No one knows how much that offset will be, but it will be there.

That reduced life, by the way, is not a unique to Sonos thing, but something suffered by all electronic kit.

So to watch TV you would want to first walk over to the sub, each surround and the Arc to turn them each on? Ain’t no-one got time for that, as the meme says.

So is it just me? Nothing weird with no turn off button? Is everyone happy with forever energy consumption or plug it off 15x & plug it on 15x

Given the energy cost of manufacture and distribution, it is questionable whether you are saving anything for you or the planet if you powered off fully every day.

I don’t understand your point about extra tasks.  Sonos speakers enter low power mode automatically shortly after play is stopped.

Stability is the other reason.  Every time you power off and on, your router has to provide a new IP address, and that is an opportunity for your router to get it wrong.  Possibly more importantly, Sonos was designed to run on its own mesh networking protocol, SonosNet.  There are still advantages to doing this and many of us still run SonosNet systems.  Taking parts of the system out of action requires reconfiguration and potentially sub-optimal performance.

Once IP addresses are reserved, I find that power cycling has no effect on stability/Sonos net. And Sonos net very quickly adapts automatically to different units being powered on at any given time.

IMO, a more accurate reason could be that as a US product, energy consumption issues were not a design priority, and adding a hard switch would also add costs. In any case, the energy saved by power cycling daily would be compensated - more or less - by the shortening of unit life via daily power cycling. So there is much less to be saved at the end of the day by the 15x activity that the OP refers to than may be seen in power bills. How much less - no one can say accurately.

What is missing is the ability to have standby power consumption per EU norms - 0.5 watts or less. The design requirement of the radios to be always on and polling must be coming in the way, but I understand that the latest units have a much lower standby power consumption than my kit of Connect/Connect Amp/Play 1 units that date back to 2013.

In my view the shortened life perspective is a non issue because of the change in Sonos support policy with s1/s2 🤷‍♀️ But many will see this different.
 

I agree there isn’t a lot of savings for an individual with a few speakers. Looking globally and the number of Sonos speakers out there, that’s a lot of speakers that could be consuming less electricity and that would be a good thing.
 

I refuse to move to S2 because I refuse to junk Sonos kit that is working fine since 2013. And I power cycle those of my 5 zones that don't see daily use. Both actions make sense to my wallet.

Do you turn off your TV at the wall when not using it? How about your WiFi router? Your clock radio? I doubt it.

Consumer electronics, by law, has to use only a certain amount of energy when in low power mode. Laws are different in the US vs EU, but the basic idea is the same.

I don’t but then again my TV uses 0.5 watts in standby but the Sonos Amp connected to it uses 7.3 watts. I turn the lights off when I leave a room, do you? 

Touche!