The traction control system is not the problem, IMHO.
The real problem is that the AWD system on the RAV-4 (and the Honda CR-v) only begin to transfer power to the rear wheels after the front wheels start to slip. By then, it is already too late to get decent traction in many situations.
If anything, the traction control should help to assist the not-so-good AWD system in gaining traction, so I would suggest that you NOT do anything to disable it. If you want to maximize your traction, you need to get a set of 4 winter tires, as they make a HUGE difference on ice and snow, as compared to so-called all-season tires, and with a vehicle like this, whose AWD system is not very good, they will make a really huge difference.