May I ask you which languages you consider as simple to learn?
I'm not sure if there's any general purpose language that's both useful (as in, allowing one to program in an efficient manner) and simple to learn.
But to name one thing that makes a language easier to learn to program in than Perl is what I call "lack of distraction". Perl syntax is rich and full, but because of that, it offers a lot of distraction - it's hard to introduce a new concept without having to explain new pieces of syntax. For that reason, I claim that C, Java, Python, LISP, Pascal and Haskell are all easier to learn than Perl. Of course, if someone already has a lot of experience in procedurial languages (for instance C) it'll be easier to learn Perl than LISP or Haskell. But as a first language, the languages I mentioned are easier. You can reasonably quickly learn the syntax, and then when you teach more advance techniques, you no longer need to focus on syntax anymore.