A White Elephant is useless. T2 is clearly not. As someone else pointed out would there be US Pre Clearance for every flight in T1 if there was no T2? I doubt it.
The simple fact is that 20 million passengers in one terminal per year was lunatic. Argue about the cost by all means but it certainly isn't a white elephant. Both terminals are far more pleasant to pass through than T1 was at its height.