If it's not a currency, what value does it have to the holder?
It should also be noted that the law determines what qualifies as a currency, not the issuer. If it looks like a duck, quacks like a duck - you know the rest.
Utility tokens are, like arcade game tokens or food and drink tickets at a fair, valuable for their use with a particular venue or service -- not for their exchange value. Generally, the law does not recognise these kinds of things as currency.
Purpose specific tokens make sense when the scope is "limited enough". The public does actually use laundromat tokens, food tickets at fairs, arcade tokens and similar things. They wouldn't take them seriously outside of the appropriate context but they definitely take them seriously within them.
