General question: who enforces DMCA? Legal protection would be nice, but if the company in question (say Nintendo in the MKW example) doesn't care and doesn't pursue legal action, does it matter in practice?
The only reason the company might care is because the use weakens their overall copyright case (e.g., Nintento's right to the Mario / Mario Kart brand). Enthusiasts don't care, so the interests are aligned, but the lawyers might not be.
The DMCA imposes criminal penalties for certain acts. The state prosecutes alleged criminal acts, not the alleged victims (in this case, owners of the copyright).
It matters not a whit if the owner of a copyright doesn't pursue legal action if some federal attorney somewhere decides that this is an important issue.
The only reason the company might care is because the use weakens their overall copyright case (e.g., Nintento's right to the Mario / Mario Kart brand). Enthusiasts don't care, so the interests are aligned, but the lawyers might not be.