Jimmy Olsen was brutally murdered early in the running time of Batman v Superman: Dawn of Justice. It was a real blink and you miss it moment; in the movie Jimmy was Lois Lane's photographer in Africa who turned out to be a CIA agent with a comically large beeping tracking device in his camera. He was shot in the head by the troops of a warlord. You had to look at the closing credits to know that this was Jimmy Olsen.
There's a lot wrong with this choice, starting on a fundamental "How could you kill the character known as Superman's Pal?!?" but what Zack Snyder had to say about the death points to a larger - and possibly crippling - problem with the DC movieverse.
“We just did it as this little aside because we had been tracking where we thought the movies were gonna go, and we don’t have room for Jimmy Olsen in our big pantheon of characters, but we can have fun with him, right?”
Set aside all the weirdness of this being fun. Look at the larger statement Snyder is making - there's no room in the future DC movies for the character, so let's kill him.
This is the exact wrong way to approach a filmmaker-driven shared universe. I would say this is in fact the number one thing you don't do in this kind of situation. You don't take characters off the board on a whim, because you honestly don't know what will happen five or ten years from now.
Let's use the Marvel Cinematic Universe as an example. Rick Jones is kinda the Jimmy Olsen of Marvel (although he's really more the Snapper Carr, but whatever, roll with this analogy), and he's long been associated with the Hulk. He's a character who has been central to the Hulk mythos, in fact, and he sort of helped found The Avengers. But at some point Marvel Studios decided not to use him, that he didn't have a place in The Incredible Hulk. So what did they do? They sure as shit didn't have the character executed - they just left him out of the fucking movie.
That small decision means that, in Phase Four or Five or whatever some filmmaker can show up and say "Wouldn't it be great if we brought in Rick Jones here?" Way back in 2008 nobody could see a place where Rick Jones fit in, but in 2021 he might really work well in some movie. And the character is there, waiting, unmolested. If that never happens then Rick Jones simply never makes it to the MCU - no harm, no foul.
That's smart planning for an expanded, shared universe. It's allowing toys to remain in the box for future players. If the DC movieverse is truly filmmaker-driven, why remove choices from future filmmakers? And why do it in such a cavalier way that doesn't even offer a character or an emotional beat? Let's give the DC movieverse the benefit of the doubt and say it survives Zack Snyder and goes on for ten more years - who's to say another filmmaker doesn't have room for Olsen in Man of Steel 5? This is exactly the kind of thinking that must go into these sorts of complicated, never-ending shared movie universes. It's exactly the kind of thinking that hasn't been going on so far.
This is just another example of how Warner Bros is backing into their shared universe without learning the most important lessons from Marvel. More than any of the other problems with Batman v Superman this is what makes me worried about the future of the DC movies.