It's just easier to have a way to view all pets as opposed to clicking here here and here to enable an option that may or may not be available to you in order to view the majority of your pets and still have to click next.
all the same though, i do like the view-all scroll-box. :) It makes it a little bit easier.
I'm also suggesting this so that we can view all pets of another user, which apparently isn't available unless that user just so happens to have view all turned on.