It seems the features on the software that support the new Denim firmware rely on multiple shot from the camera in order to gain the desired effect. If the shot to shot rate of the 1020 just can't keep up with the scene, it's in MS best interest not to make them available. Rich capture mode relies on two photos, one with and one without flash. If the scene changes too much between the two shots, the results will be terrible. For those who understand the hardware/software limitations, it may be acceptable, but for casual users it could lower opinions of Windows phone.
Just imagine someone saying to a potential Lumia buyer "my friend has the Lumia 1020 which has the best camera on windows phone, he kept trying to take pictures the other night and it didn't work. My Galaxy S5 blows it away." Sure the guy saying that may have been drunk, trying to mug the camera and moving in and out, but his opinion fair of not could influence peoples opinions of the entire product line.
The 1020 may be very good at what it does, but if it does not work well with the new software, then it's best it does not get it.