Unfortunately, DL has determined that it's FC flyers only wanted hot meals on flights of 1500+ miles.
At least that was how it was explained to us former NW flyers who got used to that great omelet for our breakfasts on any flight long enough to get a meal (even flights of ~500 miles in some cases).

For all flights under 1500 miles offering breakfast meals, you will only be offered cold cereal, a hard bagel (often inedible), a yoghurt, and a fruit or fruit cup. It doesn't matter which aircraft you are on.