Instead all database access should filter through the XF engine. The addon would invoke a function like xen_create_table("tablename"). This would allow XF to keep track of all add-on created tables, and when uninstalled, to clean up those tables automatically.
In the ideal world, uninstalling 100 add-ons would leave the database in the same pristine state as if they were never installed.
The primary benefit of this feature is that if the add-on is unneeded, or presents a security risk, its data can be gotten rid of without technical hassle.