If a wheel is a bit crooked you could ride it casually and probably not notice.
It is hypothetically possible to make symmetric rims that are in the middle. Just have a spacer on the axle, on the opposite side to the freewheel. You would just need slightly wider frame spacing, or a narrower hub.
What? The rim is centered over the hub the same whether it's symmetric or not. The only difference is where the spokes holes are on the rim.