In my opinion it's not really that high quality compared to the competition anymore (though it's still a good keyboard). They used to be, but the high end keyboard market has gone nuts the past few years and the HHKB is not really that competitive anymore for the money. They still have the reputation appeal and have kept the price high despite tougher competition, which is working for them but that is why people criticize them.
Not that I necessarily agree with that take, like I said if people are still paying what they ask for them then that's great for them.
And that's exactly what i wanted to say, quality is expensive and has not much todo with luxury in the first place, it's a high quality tool...basta.