I agree with the necessity of it, but I also find the argument "We do it because we do it." to be weak.

We do it because we lack better methods. Cart before the horse, since those better methods are often derived from cruel research, but that's the reason.

If we had a ray-gun to zap a bug with that gave us a perfect accurate reading of lactate levels within it we wouldn't resort to freezing the thing and then grinding it to dust.