If I'm right Textastic for IOS have SFTP/FTP feature so for me is natural to have the same feature is a bigger version like the one on OSX. 

If you prefer to use cyberduck use it. I prefer to have a feature and don't use it instead of missing the same feature.

This is only my 2 cent

I know that is possible to use also transmit for "mapping" SFTP drive but this feature will be great. Hope to see this soon. :-)