Maybe... the need to have a map with some additional set of accessors and/or utility functions around it ?

If you look at the code; it's literally just a map with some function around it. If you end up in a situation where you feel the need to wrap a map with some function to handle some typical needs (eg: access a random key; manage a ttl/expire for a key; ...) you might as well be using this.

The fact that the name of the functions have been taken from redis means that if/when you move to an external KV store, the transition will be trivial. It also means you don't really need to learn it if you already know redis.

I don't see becoming the #1 library on npm; with conferences and speakers debating the intricacies of its architecture. But hey it might solve someones need.