Well, the pics won't tell the whole thing. The archway being as big as it is still makes the entire area (LR, DR, kitchen) seem almost as open as it originally was, when the doors are hidden in the wall. Its a slight compromise, at the most. And the benefits over shadow the compromise.
I'm not saying the pocket wall concept is for everyone, or is even feasible in many cases, but it can be an option for some.