This is for technical reasons.  Not, as you seem to believe, Sonos deliberately and gratuitously spoiling the customer experience.  Surround speakers connect to the Sonos system in a completely different way from when acting as main speakers.  They are satellites / slaves of the main HT speaker and all the audio processing is done by that speaker.

This is also why the line in on a Connect:Amp, Amp, Play:5 gen2 or Five is unavailable when the speakers are connected as surrounds.  Ditto the wired subwoofer connections on the C:A and Amp.

This isn’t going to change.

The app is just a remote control.  How you think separate apps for TV and music would help in any way is hard to fathom.

A separate app for tv and music. The way I listen to music is not how I listen to my TV. Sonos can’t distinguish between a music album or a tv program. 
a sort of preset would work. But there is nothing like that in Sonos. 

Presets might well be convenient in themselves, but would not instantly change the nature of the connection configuration between HT speaker and surrounds.  Any preset would have to reconfigure that connection every time the type of use changed.  In effect, it would have to remove the speakers as surrounds to make them a separate ‘room’.  A preset might be a little more convenient, but would not be instant.

I can understand your frustration given what you were trying to do, but there is no way to make Airplay work to speakers that are bonded to a HT speaker.  With the benefit of hindsight, a used Play:1 for a second surround and a Sonos One (or Roam?) to bring in Airplay would have given you a good result.

It does seem a little bit of reading up on things could have helped prevent some disappointment here. The fact that One’s do not pair with Play:1’s to a stereo pair and the fact that you lose AirPlay capability when using a One as surround are both well published.

Contrary to what Sonos says (AirPlay is not available on Sonos speakers that are set up as surround speakers) this is actually possible: I removed the surround settings from my Arc with my two One SL’s. Broke the stereo pair that my (2 pc) Roam was on and AirPlayed to all 5 speakers. While music was streaming I created the surround setting in the Sonos app, and made the Roam pair as a stereo.

Voila, music in the kitchen (or wherever I put the two Roam’s) and music in the living. FunFact: Spotify can’t, but iTunes will: AirPlay to Sonos while wired speakers to my Mac will also play, hurray.

iOS15.2 with Sonos 14.0

Arc, 2x Sonos One SL, 2x Roam

No, surround speakers are not available as an Airplay target. When you added them as surrounds, they started to receive the stream from the Arc they were bonded to. This won’t work for the original poster since his soundbar doesn’t have Airplay.

Sorry but I think you have misunderstood and the process you describe doesn’t really achieve anything.  The Arc is Airplay compatible and if you play music to it then that music will also come out of the surrounds.

The scenario that doesn’t work is a non-Airplay-compatible Sonos soundbar (e.g. Playbar) with Airplay-compatible surrounds.  This is what the OP was complaining about.

Edit: @early rejecter beat me to it!

Aha! So, no AirPlay to older sounders. Well, that’s to be expected when combining newer sw on older hw.

Still, strange to me that this article https://support.sonos.com/s/article/1230?language=en_US says one cannot AirPlay to a surround system, while it works just fine at my end (at least, for now).

Cheers!

I think it is badly worded.  The intended meaning is that you cannot use surround speakers as an Airplay target.

Ah, that must be it then. Otherwise I would’ve found a feature that Sonos wasn’t aware of haha. Oh well, I just hope people don’t put off getting a pair of One’s to add to their soundbar due to this poorly worded article.