I can't speak for Taro-san, but I've never put a portable system in my pocket. They always go in a hard case and then typically in a backpack or suitcase while I travel. The utility for me is being able to play away from a monitor or a power source. Nothing about the Switch prevents me from playing on a train or plane, or in line to buy tickets.
I think of Switch as more of an iPad than an iPhone: bulkier, yes, but still designed to be portable.