Are we supposed to think this is too much HTML for one ad? Because I don't think it is.

A lot of it is URLs, and of course you have to have full URLs on an ad, you can't use relative.

As for the number of elements, there's quite a few divs but there's also more elements to an ad than people realize due to the built in reporting interface.

Sure a simple banner ad might be able to get away with only two HTML elements (an anchor tag and an image tag), but that image will end up being a lot more data than a text ad with as many elements as this one.