Today's Rant - Subplots?

Today's rant is about subplots, or at least I think that is what it is called. I'm talking about television series that start out awesome then start focusing on an inner plot instead of the weekly originals. For instance:

• X-Files. Remember how awesome X-Files was? But remember when they only started focusing on Mulder's sister? I loved each week and how they investigated things but towards the end it was just all about his sister. It's been years so I can't remember everything but that's one example.
• Touch. Touch started out as one of the most unique and beautiful shows. In fact, I can watch the pilot episode over and over. Then they started focusing on the 36 and that's all they did. This whole season was mostly just that and the show took a different direction from the show I fell in love with to the point that I didn't care to watch anymore. Since it's being cancelled, I think others feel the same way.
• Charmed. It's been so long since I've watched this but I faintly remember it going from a different episode each week to it focusing on the Heaven/Hell demon thing.
• Revolution. Now I know that this one doesn't count as much as the others since the whole reason for the lights going out is the subplot to begin with. But what started out as an awesome, fresh show only focuses on the fighting amongst them. There's not as much exploration or just plain normal stuff, which might be boring I know but it has lost something to me.

I can't offhand think of more but I'm sure they'll come to me. I know Buffy and Angel both focused on some inner plots during the last days but again, it's been a while.

Anyone else agree?