“Ye-yeah” and “baby” are open-ended expressions of love, enthusiasm and general positive energy. They might be specifically directed at a loved one, but usually they’re directed at everyone and no one and have no particular meaning at all.
Pop lyrics aren’t about conveying specific information. They’re about sound for the sake of sound. The voice in pop is an instrument, a color, a way to convey feeling. Pop music is for social dancing, so it’s about rhythm first and foremost. Everything else is just decoration for the beat. Lyrics that are too specific in their meaning can get in the way. Songs with “intelligent” lyrics are meant to be listened to alone, seated, with full concentration. If you want to dance and socialize, the music should only occupy three-quarters of your focus at most. If you’re in your room listening intently on headphones, the simplicity and generality of, say, KC and the Sunshine Band will be annoying. On the other hand, if you’re at a party and everyone’s dancing, an intricate Leonard Cohen song will be a total buzzkill.
I disagree that pop songwriters are “lazy” as Ernst Lass puts it. Writing a good pop song is harder than it looks. In my experience, writing pop is more challenging than writing something “deep” because it requires more suspension of my ego. I need to let go of my own personal whims and open up to bigger, more collective feelings.