Foam bulk, long hanging webbing and obstructions in a PFD can impair use and place the user in unsafe situations. It should contain as few parts as possible to comfortably secure to a user.
Modern electronics are becoming increasingly inseparable from our daily life. Despite this, they mostly remain mortally susceptible to water. There is no reason a PFD designed to protect your life, can not also protect the fragile things you need with you.