Why is a cascode current mirror better than a simple MOSFET current mirror?

In simple MOSFET current mirror, the load current does not follow a linear relationship with reference current (ie for short channel MOSFET's multiplying factor due to channel length modulation cannot be neglected). But by cascoding the output resistance can be increased and since output resistance follows an inverse relationship with lambda (channel-length modulation parameter), the multiplying factor due to channel length modulation reduces to one and a linear relationship is obtained between reference and load current.