Everyone keeps complaining about how Nishikata still gets teased by his wife, and gets embarrassed around his wife when they had sex and all, but the whole charm of the first series was how teaseable Nishikata was. If they got rid of that, then it wouldn't be a series of Takagi teasing Nishikata anymore to show her love, which is the point of the series.
Yeah, sometimes it gets annoying, but again, the whole point of the series is Nishikata and Chi getting teased.