Regexes originate from Perl, or they were popularized by Perl if i got this right. In Perl readable code is not ranked as one of it's top 100 priorities. Regexes could originate from J and situation could be even worse though!
Certainly making the perlre library available separate to perl encouraged its widespread use, and lots of others copied or were inspired by it.
"Popularized" doesn't seem like quite the right word though, I don't disagree with the point, but if I shout "Hey everyone let's write regex's" at the office people throw stationary at me, which is not true of other popular things!
I took a look at Raku, which claims be a better Perl maybe, or closely related but more modern, it certainly looks nice. Although i am a big fan of typed languages, Raku piqued my interest.
my Int $a = 42; # ok
my Int $a = "foo"; # Type check failed in assignment to $a; expected Int but got Str ("foo")