Poor little lass. The only time she actually walks is when she's with her dad - it's amazing she actually has use of her legs. I'm sure those boys would have been happier kicking a football (or in Cruz's case, in front of a camera) and a two year old isn't going to be paying much attention to works of art.
I used to go to art galleries when I was a child, as my dad used to take me, and that developed in me a lifelong love of art, but I doubt the Beckham's are particularly cultured (or should that be kulcha-d?) or know, or want to know much about fine art. IMO.
The whole outing just looks like a good photo op for Victoria.
And why on earth would you think that?
Why shouldn't they be as interested as you claim to have been?