If your node has multiple disks you can configure multiple Elasticsearch nodes to each use a different disk, which can protect you from disk failures if you have a replica shard configured. The drawback here is that you will use double the storage space to store each shard twice.
If you have a really large node with multiple disks it may therefore make sense to run multiple nodes on it, but I would otherwise generally recommend against it due to the overhead it adds. It is better to deploy multiple nodes across multiple servers as that would allow the cluster to continue operating if a node goes down.