It is all too easy to find a short-term solution to a problem in a process, but over time these small fixes build up in both time and effort required to implement and then remedy.
These short-term fixes are unsustainable, and fail to get the most out of your people, systems and materials – more specifically eliminate / diminish the 8 wastes of Lean.
Continuous improvement / Kaizen philosophy centers around learning and achieving excellence in business processes and systems.
With that in mind, the most obvious reasons to complete a root cause analysis are to save time and money for your organization.