The thing that is still missing in the Perl core for me is more flow control resp. non-linear flow:
One thing that I miss both in Perl 5, 6 and most languages I know of is some form of addomesticated code rewriting. We're all told that goto is evil. But we have some forms of addomesticated goto: next, last and redo, which are not evil. We're all told that code rewriting is evil. But I'm sure that there could be useful and not evil forms of code rewriting. Limbic~Region speaks about that in Doing "it" only once.