Sometime ago I was making some cleanup, at that time it seemed like a good idea to remove oxygen from my system as I'm mostly using breeze. As it turns out, my system lost ability to notify me about low battery status, which sucks when watching fullscreen movie, only indication was suspending system. By that time it's usually too late. I'm not sure if it's just a packaging issue, if it is then I should probably edit wiki to mention such detail. Or bug maintainers to add oxygen as dependency to plasma. Otherwise upstream should move sounds to a different package as breeze is preferred right now.
Unfortunately there currently is no Breeze sound theme. On a side note, I would like to implement "Urgency" hints for notifications where a critical notification, such as "your battery is running out", will show up even ontop of full screen windows.
That's one way to solve it. Some people don't want any notification noises. Oxygen sound theme still sounds alright after so many years in my opinion. I will fill a bug for Arch to add oxygen as plasma dependency, or at least change description to mention crucial function in plasma on laptops. I'm not sure what to do about this report now...