If you're a large company like Apple and one day everyone on the web and in the media starts screaming about a product defect, how do you quantify whether these issues are real or not? Well, you need to determine how widespread the problem is and do some testing. You don't make assumptions based on the loudness of the media.
Apple discovered that 0.55% of buyers complained to AppleCare and that 1.7% of iP4s were actually returned. Where else should you look for data if not from your own warranty group or channel partners? People are still not satisfied with the data, but it was sufficient for Apple to determine that there is a problem affecting a minority of iP4 buyers. Apple is addressing the solution to the MINORITY of iP4 buyers by offering a free bumper, reimbursement for an already purchased bumper, an exchange, or a refund without penalty. On top of that, Apple took the time to show that other smartphones behave in very similar, if not identical, ways. I can attest to the fact that my Palm Treo would always drop a call when held in my left hand regardless of signal strength. If I held the Treo in my left hand up to my left ear, calls drop immediately. Nobody made a big stink about that, or what a crappy network Verizon had, etc.
So, what more is Apple supposed to do? If you're not happy, get a refund. If you feel "locked" into Apple's ecosystem, then keep your 3GS which is still a fantastic smartphone and be happy. It's the CONSUMER who has the choice whether or not to buy a specific product. If you must have an iPhone but can't put up with this horrible, terrible defect that is really a non-issue, then get the iPhone 3GS.
Apple happens to feel that this issue affects a tiny minority of its customers based on hard data. Those claiming otherwise, where is their data? If you feel differently, and somehow feel an entitlement to an iPhone 4 just because, then it's time to have your head examined. These are the options people - buy or don't buy. Keep it or return it. Get a bumper or not. You have choices and nobody is twisting your arm to do anything.
Apple is one of the only companies that would go to this extent to keep its customers happy. I don't see HTC, Blackberry, or Samsung offering free cases even though their phones behave in exactly the same manner as the iP4. Yet everyone is screaming at Apple.
The next outcry will come on September 30th when Apple will announce a modified version of the iP4 which doesn't have this issue. Why would Apple limit free bumpers to September 30 unless they were planning on having the issue permanently solved by then? At several points in the presentation and during the Q&A afterward, Jobs hinted that they are looking at other ways to solve this issue and they may have a permanent solution soon.