I don't understand why people want DisplayPort
HDMI is a synchronous interface — video and audio data use up fixed parts of a frame's time. One might almost say that's it's just a digital mapping of an analog television signal.
DisplayPort is a packetised interface — video, audio, and whatever else you might want to carry over it can be sent at any time. Because of that, it's a little more expensive to implement (you need more hardware in the device), but it's immensely more flexible: you could carry multiple low-resolution video streams over a single port, or 3D video, or multiple audio streams, or even something else (IP, SMS, whatever) with no hardware changes.