I don't think it's too bad an idea. It's more about convenience and simplicity. Sure the events are dead easy, but in many cases it's just convenient, especially if you're already several subevents deep and need to trigger a scale - having some extra calculations there, or setting some kind of flag to start off a scale, would harm readability. The Fade behavior is a good example - it's trivial to set up in events, but if you use a lot of fades, having the behavior is handy. You can set it up from the layout editor/object properties, it triggers events for you like On Fade Finished, and takes care of timedelta for you too.