There was a reasoning for this, but I can't remember it, off hand. Mark Evanier talks about it in the fourth volume of the Fourth World Omnibus books. Screw it, let me grab the book and look...
...here we go:
"He had trouble getting back into his story. Time had passed, the world had changed, Jack had changed. Issues that had mattered to him in 1971 were no longer front and center, clear and present...In '71, Jack had invested his vast distaste for Richard Nixon when he wrote dialogue for Darkseid. Now, Nixon was a distant memory, Jack's anger towards him had abated and it was tough to rekindle the passions."
That might explain part of it. I rememeber reading something else about it, but part of it really was that so much time had passed since he had written the characters that they weren't the same as when he created them ten years ago. That might explain it. Hell, Kirby himself agreed with DC that Hunger Dogs was "abrupt, choppy and confusing". He wasn't happy with the final product, either.