It is extremely easy to hold the phone in a way that doesn't do that when you're talking on it, regardless of which hand you're using. If you can't figure it out, dropped calls are the least of your problems.
Holding it in the left hand while looking at it, though, is a problem, and, as my test showed, it will drastically cut your upload bandwidth. That means if you're holding it that way while talking, which we've already established is very easy to avoid doing, it will cause dropped calls. It shouldn't have too much of an effect on web browsing or the like, as those are mostly downloading. I guess what I'm saying is that yes, it's a design flaw, and a stupid and careless one, but it's easy enough to get around. Apple should do something to fix it, but it's far from the huge deal some are making it out to be.