There is no reason writing new subscribe and unsubscribe pages without the need for a login will effect the mailing is there? 
yes, this could effect the mailing.
when crating a message, there are various tokens that can be used to add user attributes to the message like user first name or last name.
If the user has not gone through the registration process, these values may not be present.
also, when creating a mailing group, you use those user attributes to include specific user, those wont be available without the user having registered in the system.
