Having feathers on the dinosaurs would be nice, but it would kind of disrupts the canon of the franchise. In the novel there's a scene where Doctor Wu and Hammond are discussing the "authenticity" of the dinosaurs; Wu wanted to genetically engineer the dinosaurs to make them more exciting to customers, but Hammond wanted the Dinosaurs to be as genuine as possible.
Let's look at the movies themselves though. What we know from the story is that they cloned the dinosaurs from preserved DNA samples found in amber, but since most of the gene sequences were incomplete they had to fill in the missing sections with amphibian/frog DNA. Now I'm not a scientist, so I'm going to guess that some of those missing sequences could have contained the genes for feathers, or it could also be possible that the feather gene was "turned off" (for lack of a better term) during the cloning process.
It's also worth noting that In Jurassic Park 3, Grant calls the dinosaurs on Jurassic Park "theme park monsters" and that real dinosaurs only existed millions of years ago, alluding to the idea that the JP dinosaurs are in fact not genuine at all. I know JP3 was a crappy movie, but it's still considered canon.
From a scientific standpoint it would be nice to have the feathered dinosaurs, but should the canon be risked for that? I'd love to know what Michael Crichton would have to say about this if he was still alive.