Why do some shows recap the entire season in the beginning of an episode?

I’m not even sure anyone (unless we have Hollywood people here?) can answer this, but here it goes…

I’ve been watching some old TV shows, like X-Files and stuff, and I noticed that each episode starts right away, after the opening credits. A multi-part episode might have a recap of what happened in the last episode. If the last episode was a season ending cliff hanger then it would probably have a recap of what happened when the season ended. That’s understandable because three months or so had passed before they started airing new episodes. Fair enough.

But now, just about every show I watch has a recap of everything that has gone on so far, even if it has nothing to do with the current episode.

I find it incredibly annoying. My memory isn’t so far gone that I can’t remember what happened last week, and if I’ve watched several episodes of the show I sure don’t need to be told what the premise of the show is. Again. All it seems to do, for me, is take up an additional five to ten minutes of show. Are the writers not able to fill up the entire 40–45 minutes (minus commercials)?