A silk bonnet is protective headwear for all types of hair. It's not something that only naturalistas should be conscious of. Yes, maybe they may be more conscious than most but all types of hair need the protection that a silk bonnet provides.
Shrinkage is healthy it is a sign of the elasticity of your hair. This means that your hair has a healthy amount of elasticity. The tighter or looser the curls of your the more or less shrinkage would affect your hair.