The problem is that this means notifications would have to behave differently with the keyboard active, as you don't want to hit a notification while you're typing, and you don't want that notification to cover up your text field either. I also think notifications by themselves are better off at the bottom of the screen, but when you have to take into account all the possible things a notification could obstruct, the top of the screen is really the place where they are least likely to get in your way. Recent versions of Android and iOS now finally have a use for their top bar and show incoming notifications there, so they don't cover anything (except notification icons), but of course there is no such bar on Sailfish. It really is a difficult problem to solve and there may be no ideal solution.