So where do you stand on this now that you've been educated? I hate saying the same tired cliche that seems to be said a lot, but if you have issues with it you should return it, you're still within the window.
Besides that, including the bumper with the iPhone, and maybe some kind of statement saying it is not recommended to use without a bumper, would have been more honest and does not make it a "defective" product - the key is being upfront about it.
the product is still defective in your scenario.
Look - I love my iPhone4 despite it's flaws. I keep it in a case - and that has nothing to do with the reception issue.
The reception issue/concern is genuine. And "just return it" assumes that people are unwilling to live with the issue. I think you'll find that many people WILL live with the issue - but not like it. And not like that they have no option BUT to use it in a case for the best reception.
The same people who can live with the issue have every right to hold Apple ACCOUNTABLE (and that's what this is really about) for releasing a "defective" product. The noise - on here, the press, etc is serving it's purpose. It's sending the message that Apple needs to stop ignoring the issue.
Returning the phone is another issue altogether and is a personal choice based on what people can or cannot live with.
Does this make sense? I know it's a bit rambly. Point that I'm trying to make I guess is that it's not a black and white issue to keep or return it. I'm not in favor of throwing out the baby with the bathwater.