AdWords API Re: Does Google allow development

As someone who did screen scraping(described in the oreilly site)
before the API became public, I can tell you that the page layout does
change quite often. Any change in the website is also that much more
difficult to propagate into your code. There is no way one would be
able to build a stable commercial product using screen scraping.
Moreover screen scraping is something that is very easy for Google to
find.

My take on this recent change is that, they want to charge money
through the Commercial version of the API for all the commercial
products. So this change in the Terms and condition is a precursor to
that.