You're spot on. When I first saw Google Wallet, I thought, "haven't Japanese cellphones been doing this for a while?" Also, I have an electronic dictionary, a DS with a dictionary game, and a phone with a dictionary. I still prefer to use my electronic dictionary when possible. The reason is simply that it is by far the best. It has the most extensive dictionary (including many computer terms), more (quantity and quality) useful examples, it also has better features for jumping across dictionaries and makes it really easy to quickly look up other words in definitions, and finally, it has much better written Kanji recognition than the DS and phone. I imagine if a phone dictionary worked this well, people would use it. It's not like I carry it everywhere with me, but like flocial says, when I'm seriously studying Japanese, I prefer to have my dictionary.