Exactly. 1999 was a lot like now. In 2001, I was calling recruiters and they literally had nothing. It's nice to think you'll never want for work and you can run out and find a great gig whenever you feel like it, but in reality you never know when the polarity is going to reverse so it doesn't hurt to keep an eye open at all times.
It's not like you're under obligation to respond, and every once in a while a recruiter may even have a pitch that merits a response.