From a evil-software design overlord perspective, I don't believe in wantarray being a good idea at all -- but you are probably glad that I'm not in charge. Technically, a function could do something entirely different based on context, not just in return type, and should it really be able to do that...

Perl says do whatever you want, but in the general case, that's asking for trouble. Feel free to disagree, that's fine, but there are many aspects about Perl that make it sloppy. Sometimes these are the same reasons that make it flexible and cool, but sometimes not.

So if people can argue Perl OO is ugly (most would agree), I can argue that wantarray is ugly... Never mind that wantarray seems to imply a true/false value from a design standpoint but actually returns undef, true, or false -- it's a three way statement.