Heh... it's actually the way I most often build my utilities - the whole idea of a 'software tool' - but there's a trade-off point between having a single tool with lots of options compared to having a lot of different tools (and remembering how everything works); in Linux parlance, you could pipe input/output data streams between cp, sed and cut or you could run a single Perl program with command line options to do one, some or all of the same functions as the individual tools.

'Your mileage may vary' as they say...