A hydrostatic skeleton would probably not be as good a choice since the exoskeleton is tougher and thus better at protecting sensitive internal parts. This can be seen in how much more numerous, durable, and successful are animals with exoskeletons (arthropods) as opposed to those with hydrostatic skeletons (annelids).
Work Step by Step
Look in this and other chapters at examples of animals with each type of skeleton, and consider which ones are more durable/stand up better to various environmental stresses (drying, physical blows, etc.).