Hmmm...
First of all, I wouldn't even bother with Adsense. 10 - 50% of all the ad impressions are blocked by Ad Blocker plugins and this number will only grow. So you already lost before you even started. Even though I am not exactly a fan of proclaiming things for dead, Adsense soon will be. If you could make $300 with the same traffic in 2009, you will be able to make maybe $50 out of that in a year or two. Depending on the niche of course. Is it worth it? No, you can use your money better.
Nargil, in life their will be doomsayers for just about everything. Particularly, from those whose bent is fueled by a lack of testing, researching and brainstorming.
Facts! Adsense is PASSIVE income.
When executed properly, few online mediums can compare.
Your statement about Adblockers. blah, blah, blah. They have been around around and will be around. They were not designed against Adsense; they are designed against blocking ALL advertisements.
You can present numbers, that you claim, prove that Adsense is not worth it, blah, blah, blah.
In the mean time, there are people like myself, who have mastered Adsense, (which really means, mastering Organic SEO) that merely shrug off your beliefs with laughter.
In the right hands and minds, one can quietly make a killing with this PASSIVE INCOME source.
Remember this; A man with an experience, is not at the mercy of a man with an argument.