Let me make this point succiently as possible :
Ratings are good : Ad dollars are better.
Ratings are good in measuring how popular a show is, HOWEVER, ratings are deconstructed daily, into various demographics that may or may not be desirable to station owners. And those demos can be spun into desirable ad rates, even if the show isn't #1.
With that in mind, you need to understand that just because a show isn't as highly rated as another in its time slot, does not mean it's not as successful.
Go ask the GM of the second place tv station in town how much money his station made last year. The number will still astonish you. Many of them gave up chasing the 1st place title years ago. As long as the demos are desirable, their jobs are safe.
Turning this back to TPIR : just because the ratings are down 15% doesn't mean they're still not making a boatload of money on it, and if the GM's are overall happy with the audience that leads into the noon newscast (which , btw, tend to be older than most other newscasts), then they're happy, and not willing to mess with a 35 year old proven formula.
Price works for two reasons : One, it's proven, and two, any replacement will likely bring in an unproven, demographically-questionable audience. Sure, Springer might do well at 11am, but what kind of advertisers will it bring in, and how will that affect the noon show dollars?