Time is money and time only marches on. Once a minute has passed, that minute is no longer available for any productive use. In the world of route planning, there are way too many opportunities to have unproductive minutes. Doing manual repetitive tasks or planning less than the best routes can yield quite a bit of time that could be spent elsewhere.
Many larger organizations have adopted some type of route optimization software in the past. Many have had successful implementations and are happy with their vendor today. On the other hand, there have also been many cases where the results were not what was expected. And, in many of these cases, a considerable amount of time and money was spent before abandoning the implementation.