Here is my take on the situation:
The tools you have been testing with your adapter are relatively low draw tools. I can work with my driver all day with one battery.
I would love an adapter for my dewalt table saw. It eats batteries.
The problem is, the size transformer (and related electronics) to run a high draw tool (like the table saw) would be big. Too big to fit into a battery case. I don't know the specs, but the table saw probably draws 35-50 Amps on startup (on 60 Volts) Thats an arc welder sized transformer.
A 30 or 40 Lb "adapter" is no longer convenient.
Also, The newer cordless tools are drawing more power than a standard household outlet will supply (albeit for a short time). Remember, an outlet will supply 1800w continuously. The battery powered tool can draw more, because there is no breaker to trip. (grossly oversimplified).