Two potential pitfalls with the route planner are 1) it is based on minimum time and 2) it offers only one choice of route. Many or possibly most drivers are indeed looking for the minimum time path between the start and the destination. However, minimum time might not be minimum distance or minimum fuel consumption. For example, a high speed low traffic route which goes over several large hills will get you to the destination quickly, but those hills could really harm fuel efficiency. A different route which avoids the hills could take a little more time but save on gas.
Providing only one route to the driver is also quite limiting. There could easily be several routes to a destination which differ only minutes in time. The website seems to always pick the single route it considers absolutely shortest. Imagine a situation where there are half a dozen routes between two places, with predicted travel times ranging from 2 hours 5 minutes to 2 hours 20 minutes. A difference of 15 minutes on top of a 2 hour drive is not very much. However, there could be other factors to choose from between the routes which are very different. For example, some routes could include toll roads and others not. Some routes might go through dangerous neighborhoods. Some routes might include a lot of hills. Some might be more scenic than others. Some might have more potholes or rough pavement.
All of these factors are things the website does not know about. Different people would weight these factors differently anyway. For example, some people would be happy to drive an extra 5 minutes to avoid paying a toll and others would not. Given these other factors, I believe it would be better to have a route planning software that offered a selection of all routes with approximately the least time. Then each driver could choose among these routes to find their best trade off between minutes and everything else.