You might want to correct the "use iStock" part of your article:
The whole point of having a logo, business name or design mark is so that it will be unique in the marketplace. How can your logo be unique if you're using a royalty-free file that millions of other people could have downloaded? Besides violating the iStockphoto Content License Agreement, using an image in this way also infringes upon the rights of the artist who created the file. If these aren't reasons enough, good luck trying to develop or enforce rights in conjunction with a logo that uses a royalty-free image.
The part about using iStock was more for temporary landing pages, say, to test out interest for a product.
I didn't know it was explicitly forbidden by their terms of service, although I wonder where they draw the line between a "logo" and an "illustration".
To me it seems like their restriction applies to using stock art as an actual logo for a real product, not as a quick placeholder for an MVP or landing page.
I enyoyed reading your article and bookmarked some links. But even using iStock for landing pages can get you in murky waters. Just ask twitter (they used a birdy from istock. After they became successful this was easily copied by copycats with almost the same url. The birdy can still be used today as it's royaltyfree). If you're going for stockart at least use it as a base for your design, not as the design.
http://www.istockphoto.com/article_view.php?ID=616