My answer is that April Fool's Day has always been ignored by the majority of the population, but the influence of the celebration can be seen in what people don't do on April 1. Even people who have never played a prank in their entire life, will nevertheless acknowledge the tradition by not scheduling important events, such as weddings, on the day. Also many businesses avoid making major announcements on April 1.
A case in point this year is Chrysler, which has announced it's going to push back the production launch of the Dodge Dart until after April 1 in order "to avoid being jinxed" by an April Fool's Day launch
But Coors Light has decided to ignore the April Fool's Day Jinx, and has announced it will debut Coors Light Iced T on April 1. Even though this immediately makes people wonder if the product is a joke -- which apparently it's not.
The most famous example of a company that decided to ignore the April Fool's Day Jinx is Google, which chose April 1, 2004 to launch Gmail. This led to widespread speculation about whether Gmail was a joke, but the speculation worked in the company's favor because Google had a history of April 1 jokes, and the timing of the launch got people talking about how Gmail seemed too good to be true (because it offered 1GB of storage space, which was unheard of at the time).