My feeling was the eat, play, sleep schedule leads to a child who goes to sleep fairly easily, and it also helps the parent understand what a child needs when he/she cries (for example, if they ate 45 minutes before, and have been awake and "playing" and then get cranky, it's time for a nap, not for more food). And that if you did this system, you were less likely to have a child who couldn't fall asleep. But that if you did, then you should do what you need to to get your child to sleep on that schedule so that the pattern works. And it worked great for me!
I don't think that is exclusively a Babywise thing, I got the same advice from The Baby Whisperer. She called it "EASY" (Eat, Play, Sleep, time for Yourself). I think it is a good flexible routine. Useful for me when I had no idea what I was supposed to do with a newborn.