We literally have an entire trilogy of movies that explain why that is a bad idea.
Fear not, we aren’t going to be growing dinosaurs any time soon as we do not have enough genetic material laying around to accurately do so. At most (concerning revival of ancient species), we can probably re-create the wooly mammoth using DNA from a well-preserved specimen found frozen in Russia, but that’s as far as it goes, unless we find a dinosaur in similar condition, which is unlikely.
Other species (none of which being quite as ancient, but equally interesting) on the supposed hit-list for de-extinctifying are the gastric-brooding frog, passenger pigeon, dodo, pyrenean ibex, carolina parakeet, wooly rhinoceros, moa, and tasmanian tiger, if anyone’s interested.
If you want to read more about this “de-extinction”, and further calm any qualms about being eaten alive by velociraptors, National Geographic has a great article on the topic (April 2013 issue).