You mean more time for forgettable filler episodes. It wasn't common finding shows that could actually justify 26 episodes per year, and most of Star Trek wasn't really an exception.
Well, no. That's the exact opposite of reality. Things are much more expensive now and take much longer; you can't film an episode in a week anymore. That's generally why there are fewer episodes. Back in the 90s, $2-$3 million/episode was considered expensive, but now you have shows like House of the Dragon coming in at $20 million/ep, and a few of the Marvel shows are even more. (And Stranger Things 4 at $30 million/ep, though that's not quite comparable since the episodes were very long.)
Everything has to be in 4K, it has to be essentially movie quality since that's what audiences expect now, and you need to painstakingly create detail that would have been unreadable on a low-res NTSC screen (or slightly less low-res PAL screen). The computers don't create the effects, they just render them and automate certain things. This doesn't make anything less expensive, it just raises the bar for what you can do...the real work is done by people, and lots more of them compared to old shows. LOTS more.
Most shows have abbreviated credits that just list the fx companies and maybe the leads, but take a look at credits for, say, the Star Wars shows...literally hundreds (and hundreds) of names, with half a dozen different fx houses. And still the studios put the artists through insane hours to the point where many of them end up quitting because of the stress. It's far beyond the days where you could get away with a few modelers in a shop who can put together some plastic and cardboard and call it a spaceship.