Fwiw the removal of condition parens isn't related to unspace at all. Rather it's related to the fact that if you allow whitespace around the method call operator, you can't infix operators beginning with a dot (for example the range operator .. comes to mind).
In Perl 5 this is less of an issue because the method call operator is longer, so not having any infix operators beginning with -> isn't a big loss.
Finally Perl 6 allows you to write .method as a shorthand for $_.method, and if we allow a blank before the dot, it's hard to distinguish a method call on the previous term from a method call on $_.
That said, such long chains of method calls tend to be rare in code I write, so the unspace really isn't such a big issue in practice.