I would like to set this down here, so that every single time I hear somebody say, "Oh my gosh, the Doctor killed those monsters, that's not the Doctor I know, this scriptwriter/script-editor/producer/showrunner clearly doesn't get 'Doctor Who', because the Doctor I remember would never kill anyone in cold blood like that, not even the Daleks, remember the scene in "Genesis of the Daleks" where he stood there outside the Dalek hatcheries, wondering "Do I have the right?", it was such a classic scene, the essence of 'Doctor Who', and Tom Baker was the definitive Doctor, and he wouldn't kill, so clearly this isn't proper 'Doctor Who', it's so sad that they're making such a lazy slapdash parody of my favorite series, it's a shambles..."
I can point out that in Part Six of "Genesis of the Daleks", the Doctor realizes that he made a horrible mistake in not blowing up the hatchery when he had the chance. He goes back in there, he hooks the explosives back up, and (with the help of a clumsy Dalek) he does blow up the hatchery. It's not due to the Doctor's compassion that the Daleks survived, it's due to their persistence and inhuman determination to survive. The Doctor's "out of their evil must come something good" speech at the end isn't a summation of his moral decision, it's just an attempt to put a cheerful front up after failing at what he tried to do. Which was, again, to wipe out the Daleks. He didn't make the decision lightly, but that was his decision. Anyone who thinks that the Doctor wouldn't do that simply wasn't paying attention.