Just read an account by a new tenkara angler who on his first trip with his brand new rod slipped, fell and broke the rod on a rock. One of the nice things about tenkara is that your other hand is free - to use a wading staff. I don't know if having a staff would have prevented his fall, but mine has prevented me from falling many, many times.
A wading staff doesn't have to be fancy. It doesn't have to be expensive. I make them frequently because they are cheaper to make than they are to check as baggage. A shovel or hoe handle, available at any big box home improvement or farm implement store, along with a bit of parachute cord makes a dandy wading staff that is both strong and quiet.
The biggest advantage that a wooden, non-folding wading staff has over the folding aluminum ones is not the stealth factor, though, it is that it will not be folded and holstered on your belt when you start to fall. I don't care how fast a draw you are, when you have started to fall you will not have time to deploy your staff before it is too late. And funny as it may sound, you don't always know you are going to fall ahead of time!
Most people with the folding staffs only seem to use them in deep, fast current, but consider this: The rocks are just as slick under 2" of water as they are under 2' of water. If you slip and fall in knee deep water you'll get wet. If you slip and fall in ankle deep water you can break rods - or bones.