I am pulling my hair out here. I have been importing photos into LR from my d7000 for YEARS exactly the same way and now, literally overnight, it won't work.
I connect via a USB cable and after I open the import dialog, I select the d7000 as my 'source' and it freezes. EVERY SINGLE TIME. It's not the card because I can open the raw files via the card reader in the computer and I've copied them that way into LR but I feel like the quality is different that way. And I've read a million forums about having a phone plugged into a USB port, I don't. There's nothing but my camera plugged in.
Is the battery in your D7000 fully charged? Importing using the USB to your camera requires power...lots of it...from the camera battery. If the battery is not fully charged, and dies during the import, files can become corrupted. For that reason I never download with the camera USB cable; always use the card reader.
I don't know why you expect better quality when importing from the camera rather than through a card reader. It is the same image data. It's your imagination. Really! Importing using a card reader is more reliable. But of course, the choice is yours.