While the point you make is certainly something to think about when travelling to developing countries, there are many developed countries out there as well where an app like this could be useful. The example given in the blogpost was Japan.
yeah while in travel, there's nothing better than pen and paper (notes, quides, maps). I can handle it to a vendor, cab driver or any bypasser and not worry that somebody will run with it or pass it to another person - you won't do that with a smatphone/tablet.
not to mention you sometimes meet elderly or tech-illiterate people and while they are helpful, good luck making them show you something on google maps on a phone or type in the address.
Never mind the safety implications of publicly showing off a ~$500 device in a crowded street market in a developing country.