"this problem" is two different issues as others have been pointing out, so my opinion differs depending on what it is.

Any phone is going to have at least some minor signal loss if the antennas are covered up. That part I understand, and am fine with. Simple concept really, cover up the antenna, and it has worse reception. Some loss is to be expected, and most phones when held reasonably do just fine.

Some phones appear to have a design flaw that places the antennas in a spot that when held in a common, but not covering way results in a significant loss of signal. This includes the iPhone 4, and potentially the Nokia E71 based on the performance shown in one of those videos. My opinion on this is lines up more with you in that I find it's a bad design. Now, if the phone has multiple antennas, this may just be a firmware issue of the baseband software not switching properly when the signal degrades. I'm still highly skeptical that firmware is going to fix the iPhone 4 though.

Overall, even if it is a major flaw, it can be worked around with a case or other method. Being that no mobile phone is perfect, I'll take this flaw over other tradeoffs I'd have to deal with on another device. I'm already hooked on the screen, like the camera, and overall enjoy the other features of the iPhone 4. I have trust in the Apple support system that they aren't going to just completely ignore the issue, though it may take a little bit of time to address. At this point the phone isn't even a week old. If the worse case situation has to happen, there is still plenty of time to return it.