You care because you do not want anyone else to 
have the image that you spent so much money to 
get and so much time to find.

It's your little piece of acetate, and it is one 
of a kind. That originality is part of what makes 
it so special. If, all of a sudden, that image is 
plastered on mousepads and shirts, it has lost a 
little of what made it so special.

The owner of the cel does not own the image as it 
is trademarked by whatever company owns the 
series. Still, you do own the cel, and you want 
to protect it.