Did you know the P5P refuse to fix the magical open for <>, it uses 2 argument open internally,

I haven't made up my mind on this yet, but what do you see wrong with that?

Like diotalevi always says: it is possible, even easy, to construct files with weird filenames on Unix. Unlike on Windows, special characters are not disallowed, only inconvenient. A user can use '|rm -rf /' as a file name, and then a simple invocation of

perl -ne 1 *
[download]

is enough to delete all the files you have write access to.

'Fixing' it, to use the 3-arg variant would entail throwing away a bunch of useful behaviours that the user can invoke from the command line.

Indeed, that is their excuse.