I now think that tenkara will work well in places it was designed for...freestone creeks and other types of cold water pocket water but for typical warm waters a normal fly rod will win hands down.
I would disagree. The fact that you've caught pike would seem to prove you wrong. The fact that you've not been incredibly successful seems to suggest little more than a learning curve.
Yes, it is true that tenkara comes with a number of limitations, and most folks will restrict themselves to small waters. And that is fine, if you choose. But the key limitations are the distance you need to cast and the ability to follow your fish.
If you routinely need to cast 70 feet, tenkara is probably not for you. But few people actually fish at such distance. The closer you can get to a fish, the more viable tenkara becomes.
Do your fish require a reel with a good drag? That seems to rule out tenkara, but not so much if you can run with your fish.
What are the limits? Beats me, but I've seen photos of some rather large tenkara fish.