I lost interest in DS9 during the later seasons, when it pretty much became a show about 21st century culture in the 24th century setting of Star Trek. It became boring to me, because it was just the usual stuff. The writers of course loved it, because it was much easier for them to do their job. And maybe some viewers too, because they could relate better to the characters, since they behaved not so much different anymore like todays characters. I personally didnt, because that is not why I watch Star Trek.
I lost interest for those very same reasons. There was conflict, drama and action but it was, like you said, the usual stuff. I didn't find it believable that the people of that time would be acting so much like us. TNG felt much more real to me and actually gave me something to aspire to.