This is not strictly true, but it is a perception I know is common. When the P4 was released initially, the only deep integration was with Reason 6 and as such, all videos/marketing materials were very Reason focused. However the integration is that deep and complete that many touted Panorama as dedicated Reason controller.
The same attention to detail was applied with Steinberg integration. There were new graphics and protocol extensions developed specifically for Cubase/Nuendo. So Nektar have approached integration with Steinberg software in the same way as we did with Reason and you can expect similar performance.