Hi, the Basic Elastic license provides some, but not all, security features. One thing it does not provide is the ability to define a custom role that grants access Kibana Application features.
If you are on a Basic license, using the deprecated role is necessary to generate CSV reports, which are another Basic license feature.
EDIT BY JOE: this isn't true, see comment below.
Sorry about the confusion. I would welcome a writeup on an issue at https://github.com/elastic/kibana/issues/new