-(4^2) = -16
-4^2 =! -(4^2)
(-4^2) = -4^2
-4^2 = 16
Still wrong, because mathematics is still not computer science; "-" functions the same way whether it is being used as a negative or for subtraction, the only difference being that the former method has an implied 0 in front (ie, -5 = 0-5).
There is a reason it works this way. Consider this:
x = -4²
y = 2-4²
I think most people will agree that y = 2 - (4²) = -14, because powers take precedence over additive operations. It would be disjointed for the first example to work differently because of the lack of a number (or if you don't think so, work with polynomials more and you'll change your mind).
Actually, that's a good example as well - nobody construes -x² as being (-x)², right? Well, why should it work any differently with a number as with a symbol? No other operations change how they work based on whether they operate on numbers or symbols.