Director Krennic orders the Death Star to fire on the Holy City of Jedha.
- The Death Star consumes kyber crystals in order to power the superlaser beam, and drains the crystals.
- Kyber crystal resources are not easily located sometimes requiring secret maps, and reportedly rare (Lothal, Illum/Starkiller Base, Jedha).
- The Empire was in the process of mining enormous quantities "all they can get" of kyber crystals from Jedha.
- Synthetic kyber crystals are too unstable.
Then, I'm guessing that you need a continuous supply of kyber crystals for the Death Star to operate.
Destroying Jedha means sacrificing a finite amount of kyber crystals. This seems like a bad move.
For the first point, I am relying on the details from another question (showing the url https://scifi.stackexchange.com/q/148320/550).
Yes, Krennic's character is puzzling to me. According to this Luceno interview, he has a reputation of being manipulative. To quote,
Orson Krennic prides himself in being able to get his way through manipulation and whatever devilish things he can come up with. He also has the ability to stay on his feet even when punches are being hurled at him. He can change strategies in the middle of things. This, combined with his innate volatility, makes him a very different kind of villain.....
And continues with
You have to take a little bit of a leap in terms of who we see on the screen versus who we get in the book. In his case, he gets even more brash and more volatile.
With his over ambitious nature, and reputation he has made an enemy of Whilhuff Tarkin. Described here (https://www.wired.com/2016/12/rogue-one-prequel-novel-clues/)
The two military officers, one a battle-hardened favorite of the Emperor and the other an overseer of engineers
We know in the film despite the successful superlaser demonstration, Krennic doesn't impress Lord Vader, even remotely. It seems that the delays, and previously undelivered promises began to call into question Krennic's management.
the scope of the project is palpable in Catalyst, from construction setbacks on Geonosis to illegal seizures of protected planets (in order to mine them for materials). The political, bureaucratic, and environmental nightmare involved in building the Death Star is only matched by Galen’s slow progress unlocking and harnessing the boundless energy of the kyber crystals.
From the film
When the battle station is finished, Governor Tarkin, the Senate will be of little concern. When has become now, Director Krennic. The Emperor will tolerate no further delay, you have made time an ally of the Rebellion. I suggest, we solve both problems simultaneously with an immediate test of the weapon.
And I thought it prudent to save you from any potential embarrassment. Your concern is hardly warranted. If saying it would only make it so. All Imperial forces, have been evacuated, and I stand ready to destroy the entire moon. That won't be necessary. We need a statement, not a manifesto. The Holy City will be enough for the day. Target Jedha City, prepare single reactor ignition. - Sir, we're in position, ready to... - Fire!
On calculated error, my opinion is that Krennic made a magnificent blunder. He's having this pissing match with Tarkin, and this is so close to his moment of glory. But all he gets is insults and ridicule. In a hotheaded state, not thinking it through and boasting to destroy the entire moon (when the battle station is not finished). The part I see the error. At the same time, I wasn't sure whether he already planned this as the way to eliminate the extremists under Saw Gerrera, together with the Jedi temple, in one master stroke. So this would be the calculated angle. In which case, I cannot think of him as simply temperamental in that moment.