The advantages of a Tenkara presentation are not exclusive or unique to Tenkara itself, and in fact, the same benefits are achieved just as well — and often better — with a long fly rod and (gasp) a reel.
I bought a Tenkara rod for my young boys a few years ago, because the longer a rod is, the more control the boys have over a drift. And the lighter a rod is, the easier it is for their small arms to cast. Long and light Tenkara rods flex easily, allowing them to load with minimal effort. That's great for both kids and adults.
I’ve used the boys’ Tenkara rod extensively — long enough to understand exactly what I don’t like about Tenkara and to understand that a fisherman can achieve the same things with a standard, long leader (long Mono Rig) setup.