Pipes also match my thought flow. "wc -l" is a good example.

"Ok, I want to read this file..."

    cat file

"Then I want to find foo"

    cat file | grep foo

"Oh, and I want to know how many lines of foo there are"

    cat file | grep foo | wc -l

In this trivial example, I could have inserted "-c" with only a few keystrokes, but on a 200 character string of commands it's faster and easier to tack "wc -l" on at the end. Plus I'm not strong enough with grep to do every manipulation I might want, so sometimes that grep will be followed by some perl, or a sort, etc.