Many retailers are going to be looking to get a good 7+ years out of an investment like this (more upscale places will upgrade more often, but the typical upper-middle class place like Macy's will expect something like this to last). Given that by far the most expensive component is the touchscreen display, it makes sense to spend a few hundred more on a processor that is more likely to still be usable throughout the entire useful life of the display (including, presumably, a major software upgrade at some point).