I don't know that it would help in this specific instance, but connecting Texas to the rest of the power grid would likely make the system overall more resilient.
The only way you can prevent damage from falling trees is to completely remove them.
Irrelevant wishful thinking. The outages are caused by localized physical damage. There is no shortage of grid power. Inter-ties to every grid in the world wouldn't help when the wires on the last mile have been physically destroyed.
Previous outages have been caused by issues with the grid rather than lines. Apparently CenterPoint is predicting that this summer power usage will near the grid's capacity and supposedly CenterPoint is known for underestimating.