i'd point out that the apple has been cultivated for something like 1000 years. its been developed into a larger fruit with fewer seeds via an extremely long period of selective breeding.
i don't think the pomegranate has had the same level of effort/attention.
Looking at other fruits grown in similar climate (mediterranean) http://www.hort.purdue.edu/newcrop/proceedings1996/V3-416.ht... it seems to me that the number of seeds and aridness of the climate are not related: olive (1 seed); Mandarin (12?). Only fig is similar to Pomegranate; fig too is filled with seeds.
"i don't think the pomegranate has had the same level of effort/attention."
Wikipedia says that "The pomegranate is native to the region of Persia and the Himalayan ranges of India, and has been cultivated in Iran, Afghanistan, Pakistan, North India, Armenia, Azerbaijan, Georgia, and the Mediterranean region for several millennia."
perhaps. perhaps they have more seeds specifically for that. with the apple, you want more flesh, less seeds. with pomegranates, since the seeds are encapsulated in the stuff you want to eat, more seeds = better. so perhaps they were bred to increase seed yield.
i don't think the pomegranate has had the same level of effort/attention.