It would be handy to be able to get and set vertex normals using polyOp methods. That way, approachable custom tools and modifiers are made possible, as well as advanced Data Channel modifier operators when using the Maxscript operator with Faces as the input. Something along these lines:
polyOp.getVertNormal <Poly poly> <int face> <int vert> node:<node=unsupplied>
polyOp.setVertNormal <Poly poly> <int face> <int vert> type:(#unspecified | #specified | #explicit) normal:<point3 normal> split:<bool=false> node:<node=unsupplied>
polyOp.getVertNormalType <Poly poly> <int face> <int vert> --> {#unspecified | #specified | #explicit}
Where both normal: and split: would only be applicable when type was set to #explicit, with normal setting the normal direction and split specifying whether the vertex normal would be the same one for all the vertex faces or a new by-face normal will be set.