It is very, very, unfortunate, but I can see why they had to be killed. So long as any of them lived, even in exile, there existed the possibility that the monarchy could be restored. The Russians are excitable about their Tsars, and much murder is done trying to restore this one or that one. Google my screen name for a particularly bloody example. Sad as it is for those innocent girls and the young boy, those children would have cost the lives of tens of thousands had they lived -- "Uneasy lies the head that wears a crown".
https://en.wikipedia.org/wiki/Grand_Duke_Nicholas_Nikolaevich_of_Russia_(1856–1929)
There were surviving Romanovs.
Grand Duke Nicholas was the cousin of the Tsar and led armies during WWI and the Civil War.
There was just no realistic way of restoring the throne.
Stalin assassinated Trotsky in Mexico in 1940, he wasn’t worried about Romanovs.
And in the event later it was millions who died.
Unless one only believes in realpolitik and not in anything higher, the only way to make sense of it is to start from the premise that the Bolsheviks were evil. Only then does the murder of children make sense. (In one of his books the late Richard Pipes described how, as the royal family was being led to the execution room, one of the young men taking them there made sure to physically molest one of the royal women, just because she was a royal and he could.)
Of course Nicholas in the several years prior had sent countless (hundreds of thousands?) of young Russian men to their deaths in insane campaigns against the much more industrialized German military.
So perhaps other than the children everyone was wicked.