Because they already have four macro primes that aren't DX?
Yes, but a 60mm becomes a 90 on the DX body and is F2.8,the 105 becomes a 150,yet both are compatible with DX and Fx. I still fail to see why they would make an 85 DX.........:shrug:
Are there issues with the performance of non-DX lenses on DX bodies?
Not that i`m aware of. I have a 35,50,85,80-200 etc,etc that work fine on both formats.
I guess Nikon know what they are doing,just seemed odd.