I had a great discussion on another site years ago about the difference between rocket and tube artillery and while I am certainly no engineer and have no military experience myself, I am unable to see how you may be able to replace both a 105mm light system and a 155mm heavier system with the same weapon. Surely they are both used in different ways against different targets? What do the soldiers who are supported by these weapons and the people who serve the artillery systems themselves think about the idea?
It's a US procurement thing. The HMMWV was slated to replace a range of vehicles, from the mechanical mule to the Gamma Goat. The HWWMV handled the higher end of the scale but sort falls short of the small/light class like the Mule, M151 and M422.
Edited by rmgill, 03 March 2018 - 1340 PM.