Retractable headphone cases are good in theory, but in practice....well... they suffer from the usual "jamming" flaws, and more importantly, they rely on a physical connection of headphones to the smartphone.
News flash: these types of headphones are disappearing and we're all moving to wireless. Very soon there will be no need for retractable headphones.
All evidence points to Apple iPhone (and other smartphone makers) introducing Bluetooth ‘sport’ EarPods later this year, and dome8 cases were created with this potential change in mind.
Typically a single wire linking each earphone is necessary to secure each earphone (and provide space for the controls), it just so happens that these wireless headphones are perfect for storing under the dome8 dome.
So, the dome8 design is future-proof; a "smart-design" for your smartphone.