I've got full frame bodies for better low light performance. Crop factor is just one issue that I really don't care about. If I could get great low light image from a point and shoot or my cell phone that would be part of my kit.
...Then again, try to get the reach of a 150-600mm lens on an APS-C body using a full frame. Financially, if not simply impossible. The opposite can't be said for FF. I have an 11-20 f/2.8 zoom (APS-C only) giving me 17mm field of view (as used on FF) that is financially reasonable.
Just crop the image from the full frame body and you have the same "reach" as that of the crop factor body - that's why it's a "crop" factor. It's not reach, it's just recording a smaller portion of the light cone produced by the lens.