Of course there is more to it than just being feelgood and catchy, - but I'm not here to get into the genre of "sunshine pop" in depth or the crossover between "sunshine" "soft psche" "folk rock" "bubblegum pop" or whatever. The thread wan't about that, just when these types of sounds started getting played.
Names of genres really are just that - names. (especially when given in hindsight) the reality is always more complex.
If you don't think When We Get There has no connection to the sunshine genre - we can beg to differ.