I know like most others that I don’t immediately throw down the TNT. It would be very useful if we could quickly pull out the TNT at the press of a button for those tight situations. It wouldn’t be immediately used like the adrenaline, it would just switch to the TNT.
You could always bind the corresponding weapon switch key to something else. That’s what I do.
Although I agree having a separate dedicated button for the TNT would be better.