Well this is interesting to say the least. In the original Japanese version of Disgaea 4 there is a full featured map editor that allows you to create custom maps. However, the American version will be modified according to NIS America. Due to differences between the policies and procedures of Sony America and Sony Japan it became infeasible for NIS America to keep the feature as it was. Instead, several modifications will be made. Users will have to make due with preset landforms instead of individual blocks. Multiples of objects other than geoblocks and characters cannot be placed next to one another(although I don’t know if this affects the preset landforms). Finally, character and map names will be randomized.
For more info check out the NISA forum post(especially page 12 where an NIS employee weighs in) or the original press release here.