I think the founder, considering that is chosen by the founder, should have all privileges automatically unless change the founder.
The problem is not everyone shares that point of view. I for one would have a huge problem if I were a user on your network and you didn't allow me to run my channel as I see fit. We can't just take the views of one or a few into consideration but the wishes of as many as possible and that simply wouldn't happen if the network administration started dictating what access the successor or any other user in any channel that is not their own gets. To be blunt, it may be your network, but it's not your channel. The channel founder chooses the successor so it's the channel founders prerogative to what access, if any, the successor is to have. Automatically assigning any level of access other than "none" would be doing just that and reducing the usefulness of successor by reducing the number of possible access combinations.
For example: How do you think a channel founder would feel if they was using their Eggdrop bot as the successor so that if their nick expired they still had access to regain founder status and your software granted full, unrestricted access to a bot while it's the successor? Especially when the documentation as well as 20 year old standard practice states to never give any bot more access than it needs just in case it gets hacked.