My kids basically play with the lego figures. There are too many fucking tiny and individualized pieces in the sets that just get broken and end up as detritus in the bottom of the lego container. I think the specificity of them actually kind of hampers creativity.
I started putting together an old set from 1983 that I loved out of individual parts on brickseek, so that'll be something to do with them when I have it all back together.
Lego's weird. It falls between toy and model, but I don't see those fish things as anything I would ever be "proud" to "display." It's not like they're high art. I think the architecture pieces are closer to something "adult," but even those can't escape the fact that they're legos.