Ask HN: When should we use an API middleware

At my company we need to connect our system right now to 4 other services.

Later, we could have many services as possible

But also, some services can connect to our system

We have 2 solutions:

1- connect the services directly but we'll have many point of connection depending on services we interact with

2- use a middleware like Zato in case to have a single point of connection

What would be the best approach ?