save on lawyer fees, save on travel time
Real rights (e.g. superficies, usufruct, habitation, servitude) are primarily attached to a property and follows ownership of the property (third parties have to respect a real right) as distinguished from personal rights (e.g. contracts rights such as sale, tenancy, gift) which are primarily only enforceable and binding between the parties (attached to the parties not the property). Real rights are governed by book IV 'Property' and not Book II 'Obligations' or Book III 'Specific Contracts'.
The distinction between real rights and personal rights is purely legal technical, real rights can have aspects of personal rights and vice versa personal rights could have elements of a real right.