Unfortunately this may have been a bit of a premature swing of the bat at a problem that doesn't really exist. Ads don't appear on this feature by default: note that the CBS implementation is showing only ads for CBS shows, and the pop-up window is co-branded. In other words, this is an opportunity for add-on revenues or marketing for those who would like to use the pop-up for that purpose. Other sites do not display co-branding or ads with the tool embedded, so clearly ads are an option but not a requirement. Since the answers provided in the pop-up is a light summary view of information available from Answers.com there is the potential to lose visitors on a click-through to more details, but if a visitor needed to look up a word to understand what you were writing about you were going to lose them anyway. The pop-up gives you a chance to keep them in context on your site before they move on out of frustration.
My first question about these tools is always: what’s the benefit to the blogger? Many of these add-ons just hold up your pageloads, direct traffic elsewhere and annoy your visitors. As others have noticed, the answer may be ad revenue: CBS is displaying ads on the pop-up, and presumably Answers will offer revenue sharing on these.
However, I sincerely doubt that anyone is in an ad-clicking mood when they view these definitions: it’s really more of an ad for Answers.com, and surely they should be paying site owners a fee for the promotion these pop-ups provide.
The real "why" of this feature is not so much ad revenues as the need for Answers.com to build more brand equity in an increasingly crowded marketplace for answers services. The habitual use of Google for looking up basic answers is now being hemmed in also by Wikipedia's rising role as a default for reference information (Answers.com includes content from Wikipedia and many premium sources). How to break out of this squeeze? Get more trend-setters to see Answers.com as a cool "must have" tool so that broader audiences will get the bug as well. Since a user doesn't have to do any downloading to use this feature on a site using the embedded service getting people to try it is that much easier - if they get the idea to double-click a word to use it. Since the provided icons from Answers.com include a "double-click any word" suggestion hopefully the training becomes fairly simple.
While I can accept that there is a bit of "embed fatigue" settling in for some folks I think that there's a certain amount of hypocrisy involved in Mashable's critique. On the very page that they mash Answers.com Mashable offers an oodle of their own links to promote their site via others' social media sites. Embedded tool users need to be careful about how they manage their own brands with a branded embed, but the preponderance of direct endorsements through blogrolls, social bookmarking links and other services makes the wise selection of tools such as AnswerTips a reasonable and productive tip for many publishers. In a world where the user is the ultimate aggregator it pays to play nice with free - need we remind you - content partners.