Dino was included in the show simply because people like animal mascots. He served a similar purpose to Snoopy in the comic Peanuts, but he didn't go nearly so far, because Peanuts was a far more perceptive comic (at least in its early days) and had a lot to say about life.

The Flintstones had nothing to say about life beyond...

"suburban men are morons, sad little boys who never grew up, they like to party and belong to weird social clubs, they are loudmouths looking for a good time, they like expensive toys, they are tyrranized by their horrible bosses, and they're secretly scared of their very demanding wives, who are greedy, shallow, brassy women who like going on shopping binges at the mall"