While Excel and SAS are powerful tools, they have serious limitations. Excel cannot handle datasets above a certain size, and does not easily allow for reproducing previously conducted analyses on new datasets. The main weakness of programs like SAS are that they were developed for very specific uses, and do not have a large community of contributors constantly adding new tools.
For a growing number of people, data analysis is a central part of their job. Increased data availability, more powerful computing, and an emphasis on analytics-driven decision in business has made it a heyday for data science.