"The battle [for Mosul] is taking a far higher toll on civilians and fighters than..Aleppo" doesn't make sense.  Aleppo has been in the "war zone" since 2011, Mosul for just 2 months.  Many thousands died in Eastern Aleppo last summer; 2,200 of them--civilians, combatants, in just 1 battle alone (Source: Syrian Observatory for Human Rights.) That equals latest Iraqi casualty figures since the battle of Mosul began in October. (CNN Dec. 2)
On the latest Aleppo offensive alone: ""hundreds of civilians have died", but "full toll is not known.": NY Times.

Meanwhile, at Mosul:
End of November, at "the main hospital treating trauma victims from the battle...medics have noted at least dozens of soldiers have died since the battle began last month." (Yahoo News) Dozens??  In November, the Iraqi civilian death toll for the whole country was 900.  (UN) Tragic...but nothing like Aleppo's toll.

Aleppo is the story. Mosul, just a footnote.  It'll be news only if it gets worse. That's good news