Are you asking too much for them? That would be my first question.
I've used both in our cars . At one point we had 2 identical cars and I had HID headlights in one, and LED's in the other. I always preferred the HID's personally.
The problem for HID use motorcycle use is the fact that not all have a high and low beam, so for a traditional headlight, they're not of much use - accessory lights only. Secondary to that, many people are scared off by the need for a separate ballast unit that many/most HID's need. This is additional wiring, including a relay possibly if the existing wiring can't feed the higher startup amp demands of an HID.
In the end, the overall simplicity of LED's often win out for most people even if the end result is sometimes not as perfectly as ideal as you may have achieved with an HID.