They did that so that it's a fullscreen experience.
But I think this is also the reason that they chose to start with the Samsung platform, because they (my NoteII at least) allow you to swipe from the top edge to display the notification bar (yes, even with Home).
That's true, and I don't know what they are doing to keep app notifications, time, and device status on the HTC phone if it remains fullscreen. I think we're all mainly talking about the feedback which the app is getting for people who have installed it on other devices which had their own launchers before installing.
WHAT?! Why on earth would they do that? Knowing my battery and cell tower status is important!