Rand's answer is good, but I thought I'd add something.
I moderate Hardware Recommendations, wherein we deal with recommending computer hardware to people who ask for it. The one thing I can say about that job is - it's a massive handful.
After a year and a half of beta our scope has only just solidified, but we haven't yet managed to communicate it effectively. There's a problem with off-topic questions; there's a problem with questions being too broad. And there's a problem of people taking it rather badly when their questions are closed because of those things. I've learned some colourful new insults, thanks to my diamond there.
I'm saying this because it illustrates what a difficult problem recommendations in general are to solve. If a full site with a team of veteran moderators and an awesome base community can't get it right after this long, the likelihood of getting it right on a site where there are other types of questions being posted for people to edit, answer, and moderate is... low. Far too low for comfort.
Yes, I know they'd be nice - but it's not going to work. Maybe it's one to revisit down the line when the site is more stable in public beta, but we should absolutely not risk destabilizing a baby, private-beta site for the sake of "Hey, I think this book is cool."