The fundamental problem of Keiko was that it was a recurring character that was a major part of the life of a regular character. If I am not mistaken, Piller and Berman had wanted Keiko to be a regular, but according to Larry Nemicek, Rosiland Chao turned down the offer in favor of a movie career. Thus Keiko tended only to appear when Miles needed a wife and family. It may have seemed life she was simply an antagonistic presence in Miles' life as a consequence.
Whatever the flaws of the character, there are aspects of Keiko and her relationship to Miles that I find interesting. When the show aired, couples faced with decisions about career more often chose to avoid prolonged separation, often giving preference to the career ambitions of one (usually the husband) over the other. One spouse (usually the wife) would be forced to carve out a career wherever the couple landed. Aspects of that made its way into the first two seasons, but not enough really to make the story meaningful. Keiko sacrifices for her husband, she gets bored, she starts up a new opportunity, and then (and most interestingly), she finds something that will allow her to pursue her true interests. The first part of that story rang true to the experiences of many, the last would have been more innovative. Being only a recurring character, Keiko's story came off as she hounds Miles, she fights with the Kai, she abandons her husband for plants, and she gets pregnant again.
