Aruba's recommendation for device density in a generic office environment is based on achieving optimal performance and user experience. The suggestion to support 30-50 devices per radio takes into account the typical bandwidth requirements, application usage, and performance expectations in an office setting. This range is designed to ensure that the wireless network can adequately support the number of devices without significant degradation in service quality. It balances the need for connectivity with the practical limits of wireless technology, ensuring that each device maintains a reliable connection and adequate throughput. This recommendation is part of Aruba's best practices for network design and deployment, aimed at providing efficient and effective wireless coverage in office environments.