I would argue that waiting for FTL is a very good strategy.

Its not there because you can no longer ignore them, but it means they are ready to leave their star system and are ready to joing the galactic community. Its also a kind of a test, as developing an FTL requires certain understanding of both science and technology, and as Harkonnen explained very well, this insures that those people have a sufficient level of intelligence to be an equal participant in the galactic community.

Also, its not really ignoring them. Its shielding them from the more advanced technology and problems that they are not ready to face. Also, they have rights. They have rights to live and to evolve at their on pace. Any such world in Federation teritory is protected from any interference by a FTL capable species. Otherwise, they would be enslaved like in Stargate universe.