They don't offer free dining on suites because they don't have to. Those who can afford $1500 per night for a suite have no need to worry about whether their dining is free. I guess it's not quite that way on the ASMu Family Suites, but those have not been on the promotion either in years past. Apparently, someone booked them with the bounceback, so perhaps that will change this year.
As for deluxe rooms, yes they have featured free dining in other years. The free dining promotion is the best deal -- by far -- if you book a value resort. At least in past years, the value rooms have been snatched up immediately with bookings for free dining. The deluxe rooms linger for a while because there are often better deals on the deluxes, like the 40% off post cards, a public code or an AP discount.
Disney has offered free dining during August/September (dates have varied) in 2005, 2006 and 2007, as I recall.