The booklets definitely do NOT just come to those who have room only reservations. I booked through Disney Destinations and booked tickets, the dining plan, and a room...and I still got the booklet (3 years in a row including this past summer).
Also, my parents didn't even book through Disney...they booked through Travelocity.com and they got the booklet 2 years in a row.
I'm not sure how true it is, but I've heard that you get the booklet if you go into the Disney website & create an account. Then you "save" different vacations & they will send you information more frequently. Then after you finally book, they send the booklet with the coupons.
As I said, not sure about the last thing but I've heard that is true from multiple people who travel to Disney often. However, I definitely know that its not true that people only get them when they book "room only" because I've never booked room only & I've always gotten the booklet.
When is your trip? Hopefully you will still get the coupons in the mail closer to your trip dates! I'll keep my fingers crossed that you get them!