Why do you think this is not possible with the push of a button?
After all...
1. It is very popular to listen to music in stereo and watch movies in surround
2. This is a technical development in the application and not something on a hardware level
It is most certainly something on a hardware level. In surround configuration, the radios are reconfigured to a one-way dedicated 5 GHz connection from the soundbar to the surrounds. This requires a series of handshakes to get right, which is why adding surrounds takes a bit of time. The reverse happens when the surrounds are removed. So therefore, a quick toggle is not possible. They could place a hot button that does the add surrounds/remove surrounds at the touch of the button, but that is not going to speed up the actual process, and doesn’t save much from the system menu commands we have today.