>In various jurisdictions, a trademark that doesn't get defended makes it much more likely that you'll lose your trademark all together when trying to stop actual infringement. If the infringers can point at others and say "look, they let others infringe on their trademark for years and only now they're going after us" that can have an impact on the viability of your case.

Oh, I didn't know that. At least now it makes some sense. Thanks.