I think part of that is because much of modern serialised stuff has its roots in the miniseries. Going back to something like Roots or Shogun, the trend has always been there. The problem is that almost any serialised show always has to have a planned end point. Even the ones that go on for bloody ever tend to have that to some extent. GoT had the books as their base for a while. Now they don’t and things have got different. But having a story to tell is important. Stuff like DSC cleaves more to something like the Buffy model (or should do) and I think could stand to go a few more episodes. The writers just need to work on their pacing. The fact we jumped ahead in DSC shows that more could have been done. The fact only one show had a planet in as well. It could have done with an epilogue ending episode, allowing the end more time to breathe. As it stands, some of that first season seems like a feature film plot spread thinly rather than a story dense with detail being told across fifteen episodes. Part of that is because of the glorified extras filling the bridge.
More balance, and the whole thing would have worked better over more episodes.
It was being out out weekly so it’s not like it was planned for binge watching.
The Buffy 50/50 model (also arguably applicable to DS9, at least later on) is definitely my preference in general. But I don't think DSC showed any significant tendencies towards it yet. Magic... is really the only episode in the whole season I could honestly call truly self-contained, plot-wise.
I definitely agree the pacing of the final arc needed serious adjustment. Lorca needed either an extra episode or a different episode to actually pay off his long-term plot properly. The 'we're losing the war' bit was way too rushed and offscreen to ever justify the shocky 'let's put the evil emperor in charge' idea, and L'Rell's treaty wasn't supported by nearly enough foundation of 'learning to understand the other', because the only thing they allowed themselves to show was Tyler being conflicted (which doesn't actually entire count as gaining insight into Klingons), Mirror Voq being a hero and Klingons on Qonos having normal lives (which, of course they do). A decompression episode after would not have been the worst idea in the world, either, though to make it work it would probably have to dig deeper into Burnham's status and make a bigger deal out of her pardon.
Says who?
Reality.