I would agree to a certain extent. However, each potential customer has to decide for themselves if its worth it. If you have a job that requires you to call out to houses either urban or in the sticks, it would be nice to have a gps system that you can rely on to get you there without having to depend on drawn out directions.
For me, if it saves me the irritation of being unsure in where I'm going even just a couple of times a year - its worth it for what i've spent (my system didnt cost me much as I already had a decent phone to run it off).