Simply stated, it is worth its weight in gold. Even if you already have adjustable ski poles that convert into probes, consider the benefits of a dedicated probe. Designed probes offer easier penetration through the snow. Probes will not ice up while probing. As it goes deeper into the snow it creates a larger hole through the snow that the aluminum shaft won't come in contact with as much.
Adjustable probes are just the opposite.
They taper to a larger diameter in the middle. Designed probes offer more options as to how deep you can probe. Adjustable poles only offer the minimum length for serious probing. Dedicated probes can be flexed into an arch and with a tarp can create an emergency bivouac. They have been used to make an extended antenna.