This are real problems. With Redis I tried to mitigate some of this problems by providing an API that allows to retrieve the full state of the database just using available commands (without having to mess with the binary dump) including for instance reading the TTL of an expiring key. This allows to create scripts that are able to convert a full database into a CSV file, and restore back the CSV file into the DB, just using the net API.
Of course with key/value stores changing the structure of the database is harder compared to SQL databases, still designing a good data layout when building your application can help a lot to make it simple to add features to the application without to resort to scripts that rebuild the data in the key/value store.
i agree with data export point. @antirez if we could clone you and distribute to other KV projects then all KV datastores skyrocket in popularity. first and foremost issue in KV popularity is ability to try quickly. if there would be a small php script that converts an sql dump into a KV datastore (and vice versa) then much more people will be trying and they know that if it wouldnt work out they can easily opt out. i hope you'll continue to be thoughtful for others who are not C++ or Java wizards. thanks!
Of course with key/value stores changing the structure of the database is harder compared to SQL databases, still designing a good data layout when building your application can help a lot to make it simple to add features to the application without to resort to scripts that rebuild the data in the key/value store.