First, and most important, is that timely planting and harvesting are easier. Most people avoid working traditional gardens in rainy weather to avoid compaction and muddy feet. But raised beds are designed for walking around, not in. So there's no reason for mud to delay operation. Spaces between beds may be left in sod, mulched or even paved with stone or brick.
Pest control becomes easier in raised beds, too.
If burrowing rodents abound, line the bottom of the bed with poultry wire or hardware cloth. Discourage rabbits and groundhogs by placing their favorite foods in a framed bed with a low fence. Beds' narrow dimensions even make it practical to suspend bird netting on flexible conduit frames. You can control weeds with plastic mulch economically, since the width of the bed can be spanned by one roll. The narrow beds help save water, too.