Every actually had a phone with a notification light? It's so convenient, I can hop out of the shower and glance at the phone while it's off, if the light is flashing I check it, if not then there's no need to even look at it. Since switching to the iPhone I find myself having to turn the screen on multiple times a day to see if I have any messages.
Yeah, having a proper notification LED is awesome! I haven't had one on a phone for years (since I last used a BlackBerry), but I miss it a little bit every time I have to pick my phone off the desk to check for notifications.
I expect that Apple will never include one on the front of the iPhone -- they seem philosophically opposed to it, for some reason -- but maybe someday they'll implement something like the Moto X's "Active Display" or WP's "Glance screen," which display missed notifications on the standby screen with (supposedly) minimal battery impact.