Website Importer must allow FTPS connections
Let's face it, any host doing things right will have plain FTP disabled. Therefore the Website Importer will almost always fail. It absolutely has to be able to connect over FTPES/FTPS. Is this even on the roadmap? It's a great feature, if only it could work.
To configure the allowed FTP connections, go to Tools & Settings > Security Policy. We recommend that you only allow FTPS connections. As result – no mentioned problem with plain FTP.
Or do you mean something else? If so, what is your feature request?
If a source server only allows FTPS connections the Website Importer will not be able to connect via FTP to import a site's content. The Website Importer needs to support FTPS connections.