SED was invented in the seventies. You may well be not faulted for
thinking that it is out-dated and old.  The basic number theory
(the introduction of zero and negative numbers) is quite old (circa
700 AD by Indian mathematicians, I may add) but no one thinks it
is out dated. Simple UNIX tools will always remain valuable for the
same reasons. Sophisticated tools are important but the simplest
tools teach you about programming and allow you to do basic tasks
with little fuss and muss.

I find it very useful to use SED and AWK for the basic filtering and
MATLAB for analysis. I can imagine misguided people using IDL and
some may be using Python.