The use of messenger bots of something that is very interesting to me right now.
I have personal experience with using messenger bots, and I have seen first hand just how effective they can be in facilitating a specific kind of work.
For me, bots accelerate the process of relaying certain information, especially within e-commerce. For instance, when I would sell a tee shirt from New Lyfe Clothing, a bot would automatically message the new customer and Facebook and thank them for their order.
Also, when the order was shipped, the customer would automatically get a message with their notification of shipment as well as their tracking information.
But there is a downside as well. At least in the near future, the bots will not be able to respond to customer service in the same way that a person can. Sometimes small issues require detail oriented tasks (such as changing and address, rushing an order, etc) and a person really need to be there to facilitate that task.
I think that bots are here to stay and over time they will become more and more sophisticated. But right now, we still have a lot to learn about messenger bots and their role in the economy.