I doubt any monk allows these images to affect their practice, but the sangha (community of ordained monastics) as a whole abides by hundreds of extremely strict rules which are designed to signal to the laity their virtue and comittment to practice. It is absolutely in the interest of the sangha to ensure that the reputation of monastics is protected.

That reputation has been building for thousands of years, and upholding that reputation -- carrying the very sacred teachings of the Buddha in a particularly strict and graceful way -- is very much part of the religious teachings.

Images like these certainly threaten to damage that reputation among less educated laity.

I myself, a convert western Buddhist no less, was surprised and a little disturbed to see these images. I imagine the shock that these images might generate for born-Buddhists and cultural Buddhists would be far stronger, and far more harmful.

Don't forget that monastics depend on the laity for alms -- their literal food, medicine, the material for their dwellings, and the cloth for their robes. The sangha was designed by the Buddha to remain interdependent with the laity. The sangha could literally die out if the laity developed distrust in it.