@Mykyl I'm sure your right
From personal experience, there is an immense amount of work that goes into adding new features to apps. With each version of the app, app developers need to:
Get the new feature programmed
Get new text translated into all of the different languages
You need to test the app using every possible scenario that the users may ever use it for. Sometimes new features can break the strangest things so you need to test EVERYTHING. The bigger the app, the longer this takes. Also don't forget that this testing needs to be done across every platform (iOS, Android and Windows Mobile) which is 3X the amount of work!
(at least for iOS) If a new feature means that you need to take new screenshots then you need to take screenshots on 6 different devices (iPhone 4s, iPhone 5, iPhone 6s, iPhone 6s Plus, iPad and iPad Pro). Once you are done taking those screenshots in English, you then need to take identical screenshots for every language you program the app for. So if the app is programmed in 25 different languages and they need to take 5 screenshots then...... *5 screenshots* X *6 devices* X *25 languages* = 780 screenshots total!
The most difficult part of this is how meticulous you need to be to make sure you test EVERYTHING and you don't miss 1 of the 780 screenshots you need!
After releasing my own app on the app store, it has made my appreciation grow for the amount of work that goes into the JW Library app!
@leoperales I just checked the JW Library's app's description and they have officially announced taking notes as a feature coming soon