It would be useful not to have to fill in a surname in the CRM. It is more likely that someone will know a first name than a surname and often the surname field will be filled with gibberish if someone is force to fill it out and doesn't know what it is.
In the latest release we've added a system option that allows you to make Last Name optional (and therefore not a mandatory field when creating or importing Contacts).
If you find any unexpected issued with contacts that have an empty (null) last name then please do let us know (although we've done some pretty thorough testing obviously).
This feature is currently being rolled out to users via phased release rings and so individual customers will start to see it over the coming weeks.