Wicker is not only weather resistant for all 4 seasons, but it is also incredibly easy to clean. There are some pieces that are made out of wood- but wood breaks down over time, can look tired and worn when left outside for long periods of time, and can be really difficult to clean and would require the use of a power washer.
Other pieces that are made from just painted metals or aluminum can also become incredibly worn when left out in bad weather. Often with these types, the paint begins to peel and fade, and there is really no way you can spruce up or repaint peeling metal and having it look as good as new. You may not like the look or style of resin wicker, but it is your best bet if you are not the type to drag everything on your patio inside whenever a storm cloud rolls in.