No it's not the case actually. I upgraded from my 2G to 3G without any penalty. With the iPhone, which is what we're talking about here, that's not the way it works or should work. Also keep in mind, the 3G[s] isn't a huge leap.
You can say that again, I paid a pretty penny for my 2G which is why I ignored the 3G. Glad I waited... 2G was good to me though, never had a drop call.