The total T(E) is the integral over kx,ky of T(E,kx,ky). It's not strange that the integral of a function is less than the individual values of the function in (typically small) regions. Take the integral of f(x)=exp(-100x) from 0 to 1. The function value at x=0 is f(0)=1 but the integral is about 0.01.