For United States trademarks, not necessarily. You don’t have to enforce the trademark to keep it; you just have to renew it on time.
The problem with not enforcing the trademark is that it opens the term up to genericization (for example, referring to all types of tissues as Kleenex). Genericization will cause a company to lose the trademark.
I don’t think kik was worried about that. It’s more likely they were bullying the guy into giving up the package name.