Perl's actually excellent at processing unstructured data, and it had a strong foothold in bioinformatics for a time. I don't think the decision was as obvious as it looks.
This is true. Bioinformatics was full of Perl scripts for a variety of (text) analyses. I however remember well that many students began to hate it soon after working with it, as it was very difficult to understand existing code. So, when given a choice, many choose Python as an alternative. And stayed with it.
For most people the thing that is hard to understand about Perl scripts is the regexp code. However, regexps looks more or less the same in any language. But, the thing is, most Perl scripts process things such as log files and similar data. Which makes the scripts highly dependent on regexps, hence hard to read and maintain. The same thing goes for any code that uses a lot of regexps.
Actual Perl code, disregarding regexp, certainly isn't anymore difficult to comprehend than code in most other languages.
