The Vacuity of the "More Troops" Mantra

Lots of eye-blotting and faux sobriety over at the WaPo editorial page today about the Mosul bloodbath.  In it, they cling unthinkingly to the "if only that bastard Rumsfeld had sent more troops!" mantra:

Thanks in part to the mistakes of the Bush administration, which has failed to deploy enough troops to places such as Mosul, it's not yet clear which side will win this fateful battle...

I'd just like to ask, though, what is it exactly that these extra troops would be doing in Mosul to prevent these attacks?  Maybe they would be going house to house, kicking in doors, looking for insurgents.  Certainly that would decrease the body count, right?  Isn't it much more likely that more troops would equal more targets?  It's not like we're weak on our right flank and need air support and an armored division.  More troops would mean one of two things: a different (indefinite colonial/nation-building style) mission, or else more targets for insurgents.

Get 'em out, already.