Usability is a single piece of an experience puzzle
A very nice point by Robert Hoekman:
We hold up usability as laudable because, sadly, most companies still have serious trouble putting their pants on correctly when it comes to usability. They need the gold stars.
Anyone in the interaction design or usability profession worth his salt knows that usability is a single piece of a very large “experience puzzleâ€. You need a strong value proposition to get users in the first place. You need a compelling product or service. You need good customer service when things go wrong. You need marketing prowess. You need something that makes you different, and better, than everyone else in your space.
For a product or service to be great, you need all these things. But you also need a usable touchpoint. A strong value proposition gets people interested in your product, but once you have their attention, a high level of usability helps motivate people to keep using it. A low level of usability deters people from using your product.