It is a cheap way to discourage rapid expanders who poorly defend their nodes. Incursion is expensive, and exponential cost increases discourages spamming of expensive abilities. If you can get away with using a probing force, don't waste resources on an incursion.
Additionally, there are cooldown times, assuming you have the quanta the addition of this ability allows you to drop a probing force at one location and an incursion at another to cut off two nodes simultaneously.
If a node is undefended it is quick easy pickings. If it is defended by only a single annihilator, then a swift bombing run followed by a probing force can capture the node.
This is particularly useful to take critical nodes deep in enemy territory to disconnect the rest of the network from your enemy starving the opposition of much needed resources. Even if they retake the node(s), the lost resources for the brief period could leave them in a serious disadvantage.