I use it for a couple reasons: one, it is installed as a base app on almost every single *nix implementation on the planet, so you can count on having it even on ancient or restrictive environments (which I work in frequently); Two, awk is frequently fast enough for most needs, and generally far faster than a number of off the shelf "modern" tools. The first reason is the one that generally leads me to its use, its ubiquity and power make it a compelling tool.