Re: Three year old Nexus 4
A lot of people install apps they don't use. If you check through the App Management you will see in the 'Running Apps' often several of those unused apps sitting in the background and also showing up in the Battery Logs.
Therefore, if they are running in the background,using battery and not being used, you delete them.
Plus also if you have 50 apps that you don't use then those 50 apps will have a constant stream of updates which will also be consuming battery, wi-fi, resources etc.
Cutting down unnecessary activity.