The special efx haven’t gotten more expensive, cameras haven’t risen in price, writers don’t seem to be demanding particular high prices, netflix takes anything that you can pitch without saying the word disney.
So what in the world happened? X-files was an amazing show and watching it you are not only entertained but you care about mulder and scully. The show is genuinely a great time. Why did they stop making them like this?
I’m going to interpret the question more as "why don’t they make shows like “The X-Files” any more than on specific quality.
The 90’s was the last hurrah of quality serialized television. You were seeing a lot of improvements in the quality of writing and willingness to push against norms and standards. You could still make a shallow serialized series and they still do today, but you could make a show back then with a lore tied together from callbacks.
So why did these kinds of shows stop? DVD sets and ubiquitous time-skipping technology meant that writers could shift from good serialized content to longer form and continuous stories. You started seeing shows filled with “previously on…” because it became the expectation that viewers watched all the episodes up to then. Streaming make it the default.
There has been a recent push to go back to a serialized model, but the economics of the industry has changed. Writers rooms able to churn out 26 shows a year have been whittled away. You also have some actors that don’t want the work schedule that comes with it. You also had a time where a show that lasted a year found it easier stay on air to get to the 100 episode minimum to make syndication valuable; there isn’t that profit motive any more.