I know I can use an adapter, but it's one more thing to carry around, lose, or get stolen. It's an extra cost to the user, and one more device dangling off my laptop.
If you lay your laptop flat on your desk. If you're using a stand, take care with your cable such that there's not adverse strain pulling down on the adapter. I'm just thankful that only cost me 2 TB-GigE adapters when I was using a Rain Design mStand with the fully specced out 15" rMBP from work (rather than killing the port itself).