Sorry, I disagree. PAR-built binaries can be built to use an external perl5X.dll or .so. Furthermore, you needn't bundle all modules you use into the binary. You can conveniently pack a set of modules into another .par file*, then ship the perl58.XXX, the library.par and any number of binary executables which use the modules in library.par and the shared library.
Now, if you say that we've just moved from a one-file distribution to a three-file distribution, well you're right, but it doesn't matter. There are virtually no substantial applications in the world that do not need a library or another. And packing three files into a .msi or .nsi installer for Windows users is not exactly daunting.
* This works as follows. Given a lib.par file containing a bunch of, say, Gtk2 modules, you can do "perl -MPAR=lib.par -e 'use Gtk2;...'". You can also "use PAR qw/lib.par/;" from your code to load the specified PAR archive and add its contents to the @INC search path. (Or actually a CODE hook, but nevermind.)