Ease of install IS or would be a factor. The onyl way it wouldn't be is if it was incorporated or weighted in with the Code quality.
Example: Someone wants to add a boolean to Mobile. they add the boolean, serialization eveything, they hafta recompile core. But they could've just used Mobile's SavedFlags.
Ex2: Someone wants to add in a bunch of stuff to when people logon. Inseatd of using Initialize and the EventSinks, they put it in an existing event sink in, say, PlayerMobile.
Ex3: Someone adding properties to a base class when they coudl've just created a NEW class than inherited from the old one.
And back to the problem of popularity, ALREADY in this thread there has been reccomendations for a popular bu not well coded script. This is my point EXACTLY.