Actually bumperettes is typically used to descibe the standard rear bumper vertical pieces. Bumper guards are the tall ones you mention. Rear bumper guards were mandatory on HD rear suspension option, so every Z/28 would have come from the factory with them. Front and rear bumper guards were optional on any model. I like the tall ones on the rear myself. Both for the look and for the fact they are correct for performance model first gen.
As far as opnions go this stuff is all subjective. Most people don't like the tall bumper guards, I love them, but only on the rear. But I do respect the decision of those that put them on the front. Car looks really correct for the era with them.