I guess you could have done the whole film as a slide show of :

Society crumbles.

They found a shopping mall.

They secure it and marvel at all the things they have.

Without a social context they suffer the poverty of material wealth.

To steal their useless treasures their fortress is raided.

Only the dead win.

I personally feel you need to have the long duration to feel the monotony of a world with all that society graves but without society.

Even the pregnancy is rendered into a burden.

Nobody to celebrate it with, no future to plan for, just shop after shop full of free baby clothes and toys.