But pressing the TC button turns off ARS, which is wheel spin control, which is what you need on mud/snow/ice...
By doing the long press it reduces the ESP/ESC (aka "sport mode") which is not about forward motion and reducing throttle control, but about braking individual wheels to maintain stability and keep the car in a controlled trajectory...
You only need it fully disabled for maximum track performance, not road driving...
And yes, you can disable it completely using VCDS (probably obd11 pro too...)...
Googling "golf gti disable traction control" produces a million hits that show you how to do it.