"As Lawrence Lessig has made clear, the internet provides potentially a more, rather than a less, regulated environment, since the digital information packets that constitute the internet can be tracked indefinitely."
...and HTML had the potential to allow for honest, scientific sharing of data, and blogging had the potential to revolutionize political discussion and reporting, and Wikipedia had the potential to become a vastly more useful tool than any encyclopedia, and DNA has the potential to free as many innocents as it convicts criminals and e-voting has the potential to eliminate election fraud...
There's a lot of potential in this world, but technology never lives up to its potential; there are too many ways we can screw it up. I agree that opponents of online gambling exaggerate the negative aspects of it, but the correct response is not to exaggerate the positive aspects: that just makes you look as stupid as they are. Worse, you're validating their misperceptions by addressing them as serious issues.
The fact of the matter is that online gambling will in the long run turn out as reputable and no more reputable than brick-and-mortar gambling -- because intelligent regulators can create physical analogues of any digital controls and vice versa (and intelligent crooks can find digital chinks as easily as physical ones.) Your sentence "After all, what makes age verification for gambling different than age verification for pornography?" brings up an excellent illustration. Currently physical age verification can work much better than online age verification (Most physical vendors at least ask for an ID from people who don't appear old enough; how many "adult-only" sites can you get into just by saying "Yes, I am old enough"?) However, current technology could be used to create digital identity services and link them to official databases (there's the potential) but to be effective, there would have to be a universal (or at least world-wide) system, and legal, economic, and political barriers won't let that happen any time soon.
So don't pretend that online gambling is anything more that a digital extension of the current gambling environment. It's not; and it doesn't have to be.