If you were in the business of Commercial Graphic Arts, you would understand.
If you are "Photoshopping" everything else together (ads, dates, fonts, colors, etc.) throughout the mag, and that was your JOB, you would most definitely "enhance" your cover subject to some degree. The idea is to catch someone's eye enough to make them want to buy the mag. We are not talking about regulars, or subscribers, but people who normally would NOT buy a muscle mag rag.
Arnold seems to be nearly ubiquitous (as far as covers go) these days. More power to him... and the graphic artists.
Gotta make a living somehow.