Nothing prevents you from handling the presentation of the soft keyboard.
Windows.UI.ViewManagement.InputPane
.GetForCurrentView().Showing += (s, e) => { /* do something */ };
Moreover, nothing prevents you from adjusting your UI to account for the height of the soft keyboard so your UI remains completely usable.
var _KeyboardHeight = (int)e.OccludedRect.Height;
I know you would prefer this be handled by the operating system. It's not. I am sorry about that. It is what it is. At least we can account for it.
Best of luck!