I didn't even notice the typo before. Everything is right then. filetype * open uses globs, which are not capable of specifying files without extensions.
filetype /\\./ open
uses open only for files that has dot, e.g. file.ext as well as for .file, while
filetype /[^.].*\\.|^\\..*\\./ open
will use open for .file.ext and file.ext, but not for .file.
The rest of files will be opened according to 'vicmd' option.