Why is every modern TV series now one big story arc?

The biggest factor I’d assume is that with streaming it’s essentially impossible to miss out on episodes and therefore miss out on plot points. Beforehand if you missed an episode you could miss out on big plot points of an ongoing story, but when you can see the episode whenever you want that’s not a problem. It also wasn’t too uncommon for shows to be showed somewhat out of order for whatever reason which could cause problems, shows having most episodes be a reset button and never mentioning the contents was more common.

OP you should be asking, “Why do all the shows I watch all have big story arcs?” There are plenty of procedurals on TV.

The format just fits better for the streaming era, or even the days of On Demand/Tivo/DVR. When it’s possible to sit down and watch 4 straight episodes of a show, seeing something like Law & Order gets old quick when you realize you’re seeing basically the same thing over and over again. But an ongoing story with broad changes in arcs and characters will keep somebody in for 10-15-20 hours because, at least in a good show, things are changing.

Serialization - don’t know how to write stuff that isn’t one long movie. Worst is seasons don’t even have clean end points anymore. Sometimes they just end a season halfway through and the following season is just picking up.

I really miss the transitional period from one episode story archs to season story archs. During the transition we got both, episode length stories that fed into a season long arch

My take: Series-long arcs give the feeling/illusion that there's a constant buildup of tension in the plot. The idea that the next episode is more important and revealing than the last. (This gets hilarious with shows like Vampire Diaries, where there's 3 bombshell moments every episode) This emotional ride keeps the audience engaged throughout the entire season, leading to high view counts. This also serves as a vehicle for word of mouth, people discussing and obsessing over what they think will happen next. Good for ratings.  Additionally, writers fancy themselves as literary experts, they WANT to write complex long plots so their show is taken seriously as an art form. Everyone wants to be the next Breaking Bad, or Game of Thrones. You can't get there with standalone episodes, at least in the genre of drama.  Standalone shows do still exist of course, they're often comedies. But people don't talk about comedies the same way they talk about drama. Partially because regular people also want to be taken seriously as media critics. Okay I've said too much. Bye.

I don’t know, but I like one big story arc much better than different stories each episode.

I hate it. RIP X files. There is no good “monster of the week” show.

That's just how it is now, used to be the opposite but now we've corrected too far.

More people prefer serialized shows over episodic.

Because filler is a lot of trash and only a few writers do it well with actual character development, and because seasons are shorter/ the audience has said in some way of metrics they see that we want serialized storytelling arcs and not small single contained episodes. Or at least that's what the industry is feeling I guess and they aren't exactly wrong when all anyone can talk about are shows like better call Saul / breaking bad, invincible, fallout, the Pitt, stranger things, shrinking, insert whatever you want really. Most any show of any genre is eschewing single contain or three - four episode stories in favor of season long *+ story arcs that happen over the whole thing or multiple seasons even. When you want to tell a more realistic story or show how things progress and lots of characters develop over time, I think it works a lot better and people really tend to respond well to it. Mostly. Flavor of the week tv has its place but it makes for a far shallower or just "easy watching" turn off your brain kind of content. People kind of moved past that or want a bit more of the content they do actually pay attention to. Otherwise it's just background noise. Which again has its place but it's not getting awards or anyone discussing it like it's must see.

Some shows bother me more than others, especially anything on Amazon Prime. They have a formulaic soullessness to everything they put out. Fallout is a great example, even with great leads like Walton Goggins, the overall show falls flat to me. The entire season strings along several different plot lines, the season ends with the a partial resolution and then a cliffhanger. The story for Lucy's brother or the overseer in season 2 could have been finished in 2-3 episodes, yet they dragged it out. Maybe we're spoiled, but shows like Game of Thrones (when it was good) or Succession could have major events occur in the middle of a season (Connor's Wedding). It makes things feel less predictable and more compelling. The formulaic shows just fail to suspend my disbelief.

Streaming is a big part of it, but so are audience expectations. On just about any show you'll have people complaining about "filler" episodes because they don't move the greater plot forward. That said, CBS still makes tons of procedurals.

I think this leads to a lot less rewatchability as well. Sopranos really executes long stories with individual episode feel so that on a rewatch or with a friend, you can watch any episode and feel satisfied.

Besides what other's have put in that there still is loads of episode shows, just they don't get as much attention. And that streaming has allowed shows that lean more into serialization have confidence in the intended viewing. There is also the decline in the mid-size "movies" which many of these from various networks seem to have been down a path of and instead get converted to tv series.

I think it's various reasons. Firstly, there are procedural modern "Case of the week" shows still airing on network tv. They're great for that format as people will finish a show and then just go right into the next show without needing to continue the series. That's what networks want because they are just trying to keep you playing ads on TV, and shows are there to keep you from turning the channel. Modern streaming, on the other hand, isn't set up like that. It's set up to put on a huge show to get you to put down money for a subscription. So that means higher budgets, bigger actors, and more money. That all means shorter seasons, higher per episode budgets, and actors who don't want to be tied down to a network procedural all year. It makes more sense to just have a movie-style arc to get you in the door, put down your credit card number, then forget you paid for a subscription when it ends. That's the modern version of "leaving the TV on the same channel all evening"

Because most people want it like that. And also with how long it takes to make TV shows these days do you really think it's a good idea to add in more filler?

Writers probably always preferred to work on continuous stories, but old broadcast TV worked best with shows that could be slotted out of order or skipping episodes.

Because the kids don’t have the attention span for filler.

Because most shows are 12 episodes max with some shows being 6-8 episodes. Only reason to have filler episodes was when it was 22 episode shows.

Because people don't want to admit that they'd rather just watch movies than tv shows.