I don't own Terminator so it has no affect on me, but I'd take a Robocop that's shorter and properly proportioned to himself, over one that looks like he was stretched out on a rack. The extendable torso is for achieving ab-crunch poses; if he's standing straight up with the torso extended it looks all kinds of wrong.
I've been thinking similarly about those long ankle pegs (height extenders) on figures like the T-800. I think they raise the knee too much and make the lower legs look unnaturally long. Achieving a more desirable height is all well and good but at the cost of the internal proportions? It doesn't sit well with me anymore.