That reflects how much the culture and media trends have changed in the interim, I guess. Smallville started out trying to repurpose the Superman backstory for a non-comics audience and strip away the more overt comics/superhero aspects, and it only gradually embraced that side more as superhero movies became more popular. But now the general audience has had plenty of time to get acclimated to superhero stories and embrace their tropes and conventions. So The Flash and Supergirl have been able to throw in all the comic-book stuff right up front.
I don't know if the culture and media have turned that much. Maybe the "no tights..." was just a bad idea in the first place?
The general audience had embraced other Superman-series before, so why not that? I guess they just wanted to make something different after Lois and Clark, which was already a little different from Superman shows before.
Those were from decades before, and they were seen as cheesy in retrospect. Besides, The WB's goal with
Smallville was to adapt the Superman story to appeal to the
Dawson's Creek audience that was their prime demographic -- an audience that wasn't interested in superhero stories but was interested in teen-focused soap operas.
Consider -- a couple of years after
Smallville began, The WB did a
Tarzan series that stripped away all the fanciful elements and moved the action to New York City, where Jane Porter was an NYPD detective and John Clayton had already been rescued from the jungle and was trying to adjust to city life. He only referred to himself as "Tarzan" once in the entire series.
And it wasn't just that network. It was the whole trend for quite a while. The Nolan Batman films tried to ground things as much as possible, to minimize the fanciful stuff and provide plausible explanations for what they did keep. The X-Men movies avoided colorful costumes and even actively mocked the idea of them. Even something as recent as
Arrow tried to avoid the costumes and nicknames and superpowers in its first season, so as not to scare off the general audience. And
Man of Steel was so embarrassed about the name "Superman" that Henry Cavill was only billed as "Kal-El/Clark Kent" in the credits (just as the latter two Nolan films billed Christian Bale solely as "Bruce Wayne" and left "Batman" out of the titles). Even Marvel has started out slow and eased the audience into the zanier stuff -- we got
Iron Man first before the more fanciful things like Thor and Thanos started to be introduced, and
Agents of SHIELD started out as a network-friendly procedural about a team of non-powered government agents before gradually phasing in more superhero/supervillain stuff. This has been the trend for a long time, to assume that the audience isn't comfortable with the more fanciful elements and thus either minimize them or ease the audience into them gradually.
But we've finally reached a point where that isn't deemed necessary anymore, since the general audience is acclimated to the headier fantasy/sci-fi stuff now. So a superhero show can just be an overt superhero show and embrace the costumes and nicknames and wild powers and all of it. And it's refreshing and wonderful.
When I started watching Smallville it was okay but in season three or four I expected steps forward towards becoming Superman. The show went on for 10 years - if the young Clark was supposed to be 16 he wouldn't be Superman till he's 26.
I believe he was supposed to be 15 at the start of the series and 24 at the end. I remember noticing that Welling was the same age at the start of the series that Clark was at the end of the series. (And yes, it was 10 seasons, but spanning just over 9 1/2 years, from October 2001 to May 2011.)
And nothing really moved forward at all, I stopped watching at season 7 or 8.
I gave up for a while in season 7, because it had become awful, but in season 8 it got new showrunners and became a much better show again for a while, although it floundered again in season 10. Clark finally broke out of his rut and started to embrace being a hero, and it became essentially a Superman series in every respect except that Clark didn't wear the costume, fly, or call himself Superman. They'd pretty much established the entire Justice League and burned through all of Superman's major foes by the time Clark finally put on the cape and tights in the very last moments (but Welling never actually did so on-camera, so it was massively anticlimactic).
And Kara was 13....while it wouldn't have taken long, Astra could've easily played that out, at least for one scene (i.e. a getaway move)
I'm not saying it should have been a long time, but they could've easily squeezed an episode or 2 out of it.
I wouldn't buy that. I knew a pair of twin brothers in high school, and once I'd had time to get acquainted with them, it became easy to tell them apart by their mannerisms and subtle differences. And that was just someone I saw for a few hours a week. If you had twins in your family, if you'd grown up around them, you'd probably have an even easier time telling them apart.