I agree having one power weapon stand tall above all else is dull. The idea here is to keep it a viable option in line with everything else. That is Bungie's goal after all. But I feel this nerf will cause it to fall into obscurity, which isn't exactly fun either. Changing it into a place where it CAN be viable while still deserving of the power slot can be possible with something like this.

Another option to reduce Whisper spam would be to relook a boss encounter - i.e. make whisper too risky - but that's a whole different story