Totally agree! Currently, there is only 1 available "Theatre mode on Galaxy Watch 4", and although you can set a lot of actions to be performed on your phone, there is only one action for the watch - to change watch face.
Similar to At home and At work routines for the phone, there should be routines for the watch to turn on / off controls based on location or activity or a setting change.
One UI 4.5 change log mentions something about Quick commands in Bixby. Have any one played with it already? Any good?
I'm surprised that watch routines are not a thing either. A few examples of watch routines that I would love;
1) When I am next to my computer/connected via bluetooth, turn off watch sounds and mobile data
2) If I'm connected to my home Wi-Fi, turn off Mobile data on my watch (to save battery)
3) Turn off all Wi-Fi and data connections at bedtime (again, to save battery)