There is code in C4::ImportExportFramework that supplies alternative code if the module File::Temp is not installed. As File::Temp is both a core Perl module and marked as a required dependency of Koha, that code only serves to add unnecessary complexity to the module and (not that this is a core concern) reduces portability to non-Unix-like platforms. In particular, the _createTmpDir routine is unnecessary. Removing it would also remove a dependency on Digest::MD5. Similarly, there's code that handles the case where File::Path is not present, but this is also a core Perl module.