Why do they even have a feature like that. When I have bad wifi coverage, usually at work, it isn’t too hard to select the wifi off and make a conscious decision to use the mobile network.
Exactly what I do, too. That's why I consider the "default ON" a bad decision.
I’m trying to figure out the crying of folks on this - smartphones in general have done similar (all without the option to switch it on or off) for pretty much the entire history of smartphones -
I noticed through participating in the iOS9 beta program that the far reaches of my home, where the wifi signal can be a bit weak - i was seeing my iPhone switch to LTE (it clearly shows it at the top of the screen, so it isn’t a secret). This behavior was less obvious prior to iOS9 because it would churn away on a poor/faulty wifi signal a bit longer.
But as I said - smartphones have flipped to cellular data when wifi was unusable prior to iOS9. What this update by Apple DID do - is it made a much simpler avenue for users to turn OFF that function. I use to turn off cellular data when I wanted to prevent it from being used (forcing the iPhone to stay on wifi - and just time out or churn away when signal got bad).
So - Apple tweets the OS to be more sensitive to wifi issues to provide a better end-user experience, and also gives us a switch to turn the feature off (again - do other mobile OS developers provide similar?) - and people complain, and blame Apple for their high data use... sigh...