If you need six months of expenses, you likely got laid off, which means your stocks are likely tanking as well, and it takes longer to get a new job. A cash or bonds emergency fund is perfectly logical. Six months isn't even that much money; in a normal 2% inflation year, that means you're losing less than 0.01% of the amount each month to inflation. The peace of mind is worth that, isn't it?

Personally I have 2 years in cash because I like to take 6+ month sabbaticals between jobs, but even that is a negligible amount due to my expense/income ratio.