In my experience so far the App Library is a pointless extra step getting to the alphabetical list. It's organisation/sorting is not very good, feels kind arbitrary, and you'll have to search to find the app you want, so it isn't really easier to use than a poorly managed home screen. The alphabetical list is better as we all know the alphabet quite well. Generally though, I'm still just pulling down on my home screen and searching if an app isn't on it.
Regarding widgets - I think a nice solution would be to turn the today view into just another home screen, but still keep it to the left of the default home screen, but let you add more going left. That way if you want to emulate the current behaviour just leave it as default - widgets screen is left of the default home screen. Other users could expand on it, effectively having Today Views (plural) when they swipe left, and app views when they swipe right (or vice verse, or their own mix).