You could perhaps argue that since their customers probably get their money primarily through ads so AP needs to generate sensationalist content to keep them happy.
They (and perhaps Thomson Reuters) themselves don't need ads to make money that is not their business model (while they do have ads revenue as well it is not key to their business )
That isn't to say AP's quality has not dropped over the years it certainly has. It seems more like given the pay journo's make these days, top talent is simply no longer interested in the field. Economic pressures of online journalism does not reward knowledgeable people taking the time to write well informed pieces, rather content mills are more likely to make money with low quality output.
To me this is more a reflection of us as consumers not paying for quality rather than industry which merely adapts to what users want and pay for ( whether with subscriptions or eye balls)
