With pop songs, there is a definite expectation of familiarity by your audience. And song styles help you get those song specific riffs or instrument backings you may spend much more time creating on your own, often leading to midifile or mp3 file use. Depends on your focus and target audience whether you need them or not and how much of your music you want to create on your own vs having it done for you. Time becomes a factor here...
A lot of ethnic music is the opposite requiring types of styles used for most songs repeatedly.