The remote cannot be used as a button in the ST ecosystem due to the lack of Zigbee grouping support in the hub right now. The DTH only adds remote to the ecosystem so that bulbs paired to the remote aren’t stolen away from the ST ecosystem.
Is Zigbee grouping support on the roadmap at all? I could be mistaken but I thought I saw posts from late '15 (back when the alpha device type handler was posted) that said SmartThings was working on that support.