more nodes means less chanche to get the network down by external force (governament, natural distater, power outage)
Also, you have the ability to query your own node for informations in a private way and dont trust third services for that
Yeah, it's important for users to run their own node so they can verify that their incoming tx's are valid but it doesn't do much more. The problem will be when only a low number of users are verifying their incoming tx's.
It doesn't make much sense for users to run multiple nodes themselves unless it's for a some sort of high availability solution.