Technical expertise is only one part of the whole picture. But it may be the part people thrust into the interviewer chair are most familiar with. Sometimes the interviews feel like a final exam and I wonder if they interviewer had final exams pretty recently.
I have been known to point out these annoying little things to my colleagues when we are hunting to fill positions:
Do the candidates' personalities mesh well with yours? Do you think you can stand being around them and working with them day after day?
Will they be reliable?
Do they seem easy to train? They will need to learn how this group does business and works together after all.
Do they express curiosity when they don't know the real answer?
Do they make things up to fake an answer? Or do they say "I don't know the answer, but based on my experience I would guess this..."?
Do they communicate well? Do they listen well?