Why can't I have a literal list slice right after a print in Perl?

Question

I see I can do something like this:

print STDOUT (split /\./, 'www.stackoverflow.com')[1];

and "stackoverflow" is printed. However, this:

print +(split /\./, 'www.stackoverflow.com')[1];

does the same, and this:

print (split /\./, 'www.stackoverflow.com')[1];

is a syntax error. So what exactly is going on here? I've always understood the unary plus sign to do nothing whatsoever in any context. And if "print FILEHANDLE EXPR" works, I would have imagined that "print EXPR" would always work equally well. Any insights?