Aside from the convenience of having the output exactly where you're issuing commands, and the ability to copy-paste the output into text documents (admittedly not without its rough spots), I frequently find unexpected uses for things like grep, sort, uniq, etc. - standard unix tools at the command line, even for supposedly purely visual output.

As an example, for the last chart shown:

  cat gencode.v35.annotation.gff3 \
  | grep -v '#' | grep 'gene' | cut -f1 \
  | uplot count -t "The number of human gene annotations per chromosome" -c blue
  | sort

gives an alphabetical ordering, rather than by descending count. Or you could search only for a single row of interest, or filter out duplicates, or ....