Remember though that the requirements change for the item and an additional level requirement penalty is added as a hidden affix.
It's +5 rlvl for normal -> exceptional and +7 rlvl for exceptional -> elite, and +12 rlvl for normal -> elite.
Some normal items (uniques) have properties that other uniques don't for instance; goldwrap (high MF for a belt), venom ward (nice +max resist and reduced duration together on one item), etc (I could go on but I think you get my point).
If goldskin has a property that make it special to you then by all means upgrade it, however some items just are not worth the runes to upgrade, its all what you value.