So I've tested with the copy features command in Toolbox and python. It is not creating a spatial index table or index (in Oracle) as it says it will do by default if a spatial grid is not designated.
According to the documentation, ArcGIS Desktop
a Feature Class has to have a spatial index table an dindex when using ST_geometry (which is what we are using). So how is the feature class drawing fine without one? I'm using 10.1 on a 10 SDE in Oracle 11g.