This line of criticism re the Libs' English ad is as predictable as it is mis-guided. You don't want to introduce your leader to the public with an attack on the other guys. In the words of Jack Stanton, you never want to be the first one to act like an asshole. And when Nicholls writes
Well strategically speaking they make no sense. These kind of positive, hokey ads only work if your guy is way out in front.
...he misses the point entirely. They also work if you want to give the audience the impression that your guy is out in front, at least figuratively--that he's responsible, has a positive vision for the nation, and isn't interested in partisan cheap shots. You don't want to give the impression that he's a perpetually angry jerk with no class and no couth, if only because the Torys have that demographic sewn up already.
I'm sure the Libs have a darker line of campaign rhetoric at the ready, but this is not the time for it. Nicholls problem, and the problem with Conservatives generally, is that for them, if you're not accusing someone of being a pedophile or a commie, its just not campaigning.