I also think that if she had been happy all the time and there hadn't been any tension in their relationship then we'd see exactly the same sort of thread we have right here, except the complaints would be more along the lines of, "That was so unrealistic! Keiko threw away everything when she moved to DS9 but then was the perfect submissive little wife when she got there! How stereotypical!"
Is there really away way to make her a stronger character, and still be a wife to the only major non-officer, and being only a civilian? If Keiko and the chief were officers, she could be more important. Still, she was a better character then Captain Picard's barber and looked blue.