Your CSV peeking epiphany was in essence a matter of code vs. tools though rather than necessarily CLI vs. GUI. On Windows you might just as well have discovered you could fire up Linqpad and enter File.ReadLines("massive.csv").First() for example.
In a real production environment that command line would be put into a script parametrized with named variables and the embedded awk scripts would be changed to here-docs.
Sounds good although at that point it's just programming, and there are tools that are cleaner and faster and more robust than piping semi-structured strings around from a command line.
The one real benefit that can be argued is ubiquity (on *ix). Not every system has Perl, Python, or Ruby installed - or Hadoop for that matter - but there's usually a programmable shell and some variant of the standard utilities that will get something done in a pinch. If it happens to be 200x faster than some enormous framework, so much the better.
That code you're replying about was carefully and correctly written. You just replied as if you know how it works just so you could look like you know what you're talking about.
If you're unlucky, someone who actually knows how File.ReadLines() works will show up in an hour or two and explain that it's lazily evaluated.
