Maybe not exactly what you're talking about, but being able to easily try something in a one liner, or a small script is something I use all the time. I learnt to program by typing random lines of code into the BASIC shell on my Amstrad CPC 464, running them, and seeing what it did. I learnt Perl in a similar way.

I still use one liners in Perl to figure out things like this (altho not as often, and usually relating to a specific module I haven't used before). Other languages make this sort of thing much harder. PHP requires you to have some sort of web server to try something (altho I think there's a CLI these days). Don't even get me started on Java.

So for me, I think this is definitely one of the reasons I ended up a Perl programmer.