You can have the most usable system in the world but if it doesn't provide a useful, helpful service, you're just wasting your user's time.

Some would accept poor usability if they get what they need, if the total experience is great.
Some would reject perfect usability if they are not rewarded with a useful, engaging experience.

If the outcome is valuable enough, people will forgive some friction.

So please, be usable and useful.

Usability isn't enough, make it useful.