My guess is to allow the use of exisiting switchmode power supplies which already run on around 340VDC (rectified & filtered 240VAC).
It's a stupid idea though, apart from the switch issue (are we going to see a return to tumbler switches?). Are we going to have two light bulb sections in the supermarkets? One for 350V and the other for 230V? Think of how long the 350V bulbs are going to last in areas with conventional 230/240v mains!
What of the insulation requirements too? I have a set of British electrical engineering books printed in 1931. Apparently the reason for 250V being the highest voltage for domestic consumption was because the fire authorities felt that anything higher would compromise the insulation available at the time.
Someone must have a lot of idle time to think up strange new supply voltages and frequencies...we've been through all that over the last hundred years.
