Tesla doesn't WANT to increase demand right now. That means scaling up manufacturing, which is extremely expensive and still kind of politically shaky. MUCH better for them to put a ceiling on demand with high prices, and simultaneously increase their profit margin. More money in the bank for later expansion, less debt, and less commitment to potentially flawed early designs.

The Tesla Roadster was ridiculous, but the cash it generated and the lessons it taught them gave them the opportunity to scale with the S sedan. Now the S sedan will give them that same cash/lessons combination to expand with whatever comes next.

This is no different than scaling a software startup, if you think about it.