Into-wind aileron on the TO run and through rotation performs two basic functions: a) countering some/all of the anticipated rolling tendency and b) letting the PM know that the PF is aware of this and is doing something about it (conventional controls).
I've never understood the into-wind aileron on the landing roll obsession.
I think it comes under the heading of good airmanship. Some people I fly with (not many) effectively let go of the controls as soon as a wheel touches the ground. In benign conditions this doesn’t matter but in a gusty crosswind there is still opportunity for uncommanded roll, especially if the aeroplane is not level to begin with. Add in slow spoiler deployment and high body angle and you are right in the danger zone for airframe contact.
Put it this way, it doesn’t do any harm and could be greatly beneficial, so why not? It’s a good habit to have and can be essential on smaller aircraft. Aerodynamic effects do not cease on first touch with terra firma...