The added bonus for content creators came in the analytics these cards gave you- you were able to access accurate data regarding the number of clicks through to your site from Twitter, the most popular links, and the amount of impressions your content got on the site. With that data, you could find a lot of things out. In early November last year, Twitter quietly ditched the feature without telling anybody. In January they released a statement, burried on one of their sites with less than 200 views. The analytics dashboard reads 'enable Twitter cards to view this data', prompting many who can't find this statement to panic.
Twitter has the absolute right to ditch popular or useful features. However a company providing no information for two months, then ditching a feature in a statement hidden in the depths of a spin off site, while retaining messages suggesting the feature is not enabled rather than discontinued, is a worrying sign. Twitter has already ditched Vine- one of its most expensive accuisitions. How many more features are set for the cut?