Look, the raison d'etre electorally focused political party is to win as many elections as possible. To argue that winning more seats is somehow a negative for any political party is exactly as stupid as arguing that it is bad for a sports team to win a championship. To even attempt an argument that winning an election is bad for a party is to enter the final level of concern troll mastery, where you begin to take on a light glow.
Arguing that 30-minutes of unchallenged, scripted, primetime coverage on all broadcast networks (I believe it is every broadcast network, anyway), isn't much smarter. Obama has effectively purchased another one-half night of Democratic convention coverage for himself. This TV spot presents about as much risk as the Democratic National Convention poised for him. Of course it could suck and backfire, but you take that "risk" with every campaign speech, every interview, and every piece of paid media in a campaign. However, no one holds back from giving campaign speeches or paid media because they might suck. You work hard and have staff to make sure these things don't suck.
Arguing that tonight's commercial could hurt Obama is akin to arguing that campaigning at all could hurt Obama. It doesn't quite give you the concern troll mastery glow, but it does mean you have almost achieved that level.