Popular Symbolism has a huge and immensely interesting post on zombies as metaphors for human fears throughout the latter half of the 20th century and into the 21st.  We highly recommend reading it.  (It even has footnotes!)

Dawn of the Dead is analyzed in the section on zombies and consumerism:

The constant urge to buy things, driven by unconscious desires exploited by unapologetic advertisers, reduces man to ‘pure, lobotomized instinct’, as a scientist in the movie puts it. This subliminal theme is taken to even further extremes when the ‘heroes/heroine’ in the movie decide to take refuge inside an abandoned shopping mall.

After they have purged it [the mall] from the zombie menace, the keys to paradise are at their fingertips. They lock themselves in, barricade the doors, and they consume, and consume, and consume. Amusing themselves with trinkets, dressing themselves up in elaborate costumes, playing videogames. All the time, they hope things will just return to normal if they just disengage from the realities of the situation (a society disintegrating, more and more ‘zombies’ being drawn to the mall) and have a ‘good time’.