I think instead of not doing interviews, if you were encountering the problems you mention, would be to get better at interviewing. Interviewing is not about asking "How good are you at X? How good are you at Y?" You are trying to gather a lot of different information:
- Is this person's long term goals consistent with my goals for the position?
- How well does the candidate communicate?
- Personally, I like to ask what the person has been doing to improve their skills, on their own. Reading books? Working on an open source or their own project?
- Will this person fit in with my team, and the company at large?
Amongst other things unrelated to "How well you know X."
The best tip though, is to hire physicists. They're cheaper, sexier, smarter,...
Sexier and smarter, certainly, but I don't know about cheaper. Maybe better to say "a better value"? :)