So what!! it's not just usability lah

Usability has been key topic of my lectures. But . . .but.....just usability ain't all that important, its like a best Pakistani dish without salt. According to wordnet usability is the quality of being able to provide good service, its about user satisfaction, give top priority to your user. However what if the design is simple and usable but the end result is frustrating. I spent hours to search for the cheapest ticket and finally got one but when I was about to key in credit card details, it just crashed.
Another night mare when I tried to contact the agent from Terminal A site via their chat line but to no avail. The site have good usable design elements; however, it failed to provide customer satisfaction (see attached screen shots).
p.s. I waited too long for the agent, I reckon the agent must have gone on holiday too!!