Hi Gerald. I'm the main dev working on the new Unity Assets.
Sorry you're not getting the experience you want. I'd like to address some of your concerns.
For customizing your hand graphics, I might be missing the problem. You can modify the RiggedHand prefabs and apply any shader you like. There is an example with toon shading (default i think) and an example with a specular shading in the Scenes folder. Then use the modified prefab as your graphics model.
For the hand physics, you can modify the RigidHand prefab. If you just want the finger tips you can delete all the other bones in the prefab and use that as your physics model. You can also select all the colliders in that prefab and make them isTrigger.
The reason for separating out the physics from the graphics was because of integration with Unity's physics engine. If you have a hand rig where you set the rotations of the joints, you can't just put colliders in the rig. You need to move a collider using velocities and angular velocities to get the desired interaction.
I hope that helps, feel free to PM me if you have any specific questions.