The point of this break down is because some things (and it's not a perfect separation) really won't be shared between mailing lists. OTOH, you might want site-wide bounce settings that all lists will inherit and shouldn't be able to change. Other sub-styles give the list its "flavor", i.e. an open discussion list where anyone can join just by confirming their email, or a one-way announcement list that can't be unsubscribed from because it's an "all-employees" roster.
I already had this idea in my mind and that's why I have divided all the styleable attributes into three categories: 1: Site owner level attributes. 2: Domain owner level attributes. 3: List owner level attributes.
Suppose attributes related to bounce-settings come into site owner level attributes(I have not yet decided which attribute will fall in which category) then only site-owners would be able to set them and once these are set, the list owners would be having only two options. Either apply the existing style as it is or create a sub-style and adjust the list owner level(not site-owner level) attributes(to give their list "flavor") and then apply it. This way they would be able to make their list an "open discussion list" or an "one-way announcement list" without being able to edit the bounce-settings.
Regards, Harshit Bansal.