Please correct me if I'm wrong, but scientific journals (including physics journals) are published and survive based on economic principles. A journal is more marketable the more it satisfies the consumer's demands.
What are those demands? Do physicists want more articles about string-theory than they do about twistor theory? String theory wasn't very marketable a few decades ago. How much of peer review is governed by "fashion" and ordinary market forces?
Is there "peer pressure" in physics? If so, how much?