Currently the client when attempting to login with a character when the server is full displays such a message and kicks you back to the start of the launcher with Start, Opening Movie, Configuration, and Exit.

This exasperates server load as it requires a few HTTP(s) requests to fetch the server list for JP as well as NA / EU. Returning the users to the character selection screen instead will drop a large amount of requests to these service APIs that generate the lists. The only reason to fetch the data again in this scenario would be if the user clicked the "World" tab to display the list of worlds in which case you would refresh the list.

I would also greatly recommend a level of cache validation in the client itself to prevent me from being able to DoS these service APIs by attempting to login during peak hours repeating the cycle. If the list was successfully fetched less than 1 min ago use the cached data and do not fetch the list again.

These are some basic suggestions you could do to get more mileage out of the over burdened servers. In time these problems should subside but there is still no reason to use the extra bandwidth or cost involved even after load drops and the 'new and shiny' factor wear off.