Toyota didn't design and build the Highlander to compete with the Miata or Cayman or whatever. This thing is about selling high-margin SUVs by the boat-loads, and it works. People love them. They're everywhere. 95% of people see cars as appliances and they want something well made, reliable, and comfortable.
My own Highlander is probably the most boring vehicle I've ever owned. And because of that, it's awesome! It does what it was designed to do, and very, very well.
The only thing I don't like about the newest HL is the change away from full time AWD.