For most mobile app developers the basic thing that would keep them as well as their apps in constant use is the scope for improvement that they need to keep an eye out for all the time. without improvement in these apps, it doesn't take them much time to go out of favor or of use which is why constant evolution is a must.
But for that, it is crucial that you know which sectors need improvement and that could only be done when you have the correct analytical data on them and that requires the right questions to be asked.
A developer should keep in mind his audience as well as why they are or would want to be engaged with any particular app.