First, it's time. Science (like time) waits for no man. Most science standards that were used prior to NGSS adoption were drafted in the 1990's. Science and technology have developed rapidly in the past 20 years. Much of what impacts us daily (e.g. digital wave technology) isn't included in the older standards. Check out this infographic for other science and technology advances that have occurred since 1995.
Second, current issues in science (think climate change and reduced funding for scientific research) have demonstrated that we need to improve science literacy in the United States. For example, 97% of scientists who study climate science affirm that the climate is warming yet a large portion of the electorate and elected officials don't believe that climate change is happening, or they question the presence of human impact on climate change. Regardless of our views on controversial issues, we need to ensure that we are producing graduates literate in science so they can make informed personal and political decisions about scientific issues.
Beyond a scientifically literate population, we need scientists and engineers. Not only will new standards help prepare students for college science and engineering courses, they will also ensure that all of our students are introduced to science and engineering so they can make their own decisions regarding pursuing either after high school.
In many instances, the "old standards," reduced science to a large list of facts to be memorized. This approach to science doesn't match the approach used by scientists. The NGSS approximate the work of scientists by integrating knowledge and practice throughout the science curriculum. This approach will not only increase learning, it will also inspire a new generation of scientists because they'll see science as more than memorized facts discovered by some long-dead scientist.
Are new standards the magic bullet to fix all that's wrong with science education today? No. Are they easy to implement correctly? No. Are they worth it? Yes--our students deserve nothing less than a science education that puts them on the path to careers in science and engineering (if they choose) and the path to becoming critical consumers of science in their adult lives regardless of their chosen careers. Won't you join me in the hard work of ensuring every child has this opportunity?