Google is stupid to run radio ads for Adsense

Just heard a Google ad on a local music radio station. Basically it is telling bloggers who blog about mom life or other stuffs to check out google adsense to generate revenue on their blogs. I don't know how long Google has been running such ads on radio. Maybe it's one of her fightback to Bing's ad campaign. But I really think this ad is totally a waste. First of all, using wrong media to target at online bloggers. I am not saying bloggers don't listen music radio, they do. But should online media be more effective here, comparing with average advertising cost on radio? Second, does Google assume a lot of bloggers don't know adsense? Serious bloggers have been hunting for best revenue generation tools for long time and most blogging platforms already have adsense built in. So seriously, what does Google want from such an advertising campaign? Does it just have too much cash to throw away?