I don't find it difficult to have a day or two of rain on a trip; the tough times are when it rains day after day after day, or at least if the cloud cover remains such that the vegetation stays wet and it's overall wet and cold. Then you start thinking about using body heat in various ways to get things dry (or at least "less wet") and some careful thinking is in order for the backpacker that carries relatively little in the way of gear and spare clothing. It can indeed be a challenge, but hopefully one that's just a challenge in terms of comfort and happiness, and not so much of a safety issue.