I don't think follow bots are a good idea, because they make the federated timeline the same on every node. Without them, the federated timeline is still an expression of the interests of the node's users.
@lambadalambda IMO, followbots also express the interests of the instance's users and admins. People would end up subscribing to those people directly, because these are usually people who frequently pop-up in conversationss with people who are already in the instance's TWKN timeline.

Better conversation-retrieval would also help.