Dude, did you not read a single review before purchasing the thing? An uneducated consumer is a companies worst enemy.
First of all, the "75%" is not plastic, its a delrin/graphite composite. As far as the back panel, it's always been a separate thing since some people like having a bare back phone. The reason for the switch to the composite was because, as many of the other threads around here re: element and several others will show, aluminum completely frags reception, pure and simple. Unless you're in the very strongest possible signal areas, Aluminum is like trying to use an ipod to make calls or use data in the wild - its purely an act of futility.
Finally, if you're going for protection, try ordering a full coverage case - beit an otterbox, or the atomic diamond back (my review in that thread shows some reception issues, but the diamondback most definitely protected my phone from a NASTY smack against my AC unit). Just like the element case and many others, atomic is manufacturing a fashion case. It is designed to improve the look of the phone, protect from "Death grip" (thats why it covers the antenna, or as you call it "the stainless steel band that doesnt need protection") and yes, give just a little bit of protection to the sides of the phone. It protects far better than the bumper, which was apple's original solution...
So seriously dude, you bought the wrong piece of equipment pure and simple. Why you would believe a bumper style case from ANY manufacturer would provide great protection is beyond me, but it seems like you have unreasonable expectations. I find it absolutely hysterical that you're blaming a case manufacturer because you ordered something that was not designed to do any of the things you're complaining about.
Effing ridiculous.