1. Ansible is rolling out to more end users, and they are hoping the interface is displayed in "traditional" languages. 
2. Similar to previous point, non-technical users like "auditors", or "senior managers" are asked to "review" existing logs, or to "approve" a workflow in Ansible Tower/Controller, a localized user interface can make them feel more comfortable.
3. For the customers in a locked down session and having no control over the browser language settings.
Summing up, if we want to make Ansible Controller/ Event-drive Ansible Controller more successful, it is time to consider adding more language support.