What are the downsides of a twisted wheel? After a collision where somebody fell on me, my front wheel is twisted to the point that it slightly touches the brake once per revolution causing a soft screech. Logistically, I can't get to the shop to repair it right away. 

First, is this condition dangerous? Should I stop riding the bike until it is repaired? 

Second, if there is no danger, what are the pros and cons of repairing it at all as opposed to leaving it that way? This is a cheap bike I bought used, and if they need to exchange the whole wheel, it might cost more than I want to pay. I find the sound slightly annoying, but not terribly intrusive, and if there are other influences on the riding experience (slower speed?) I haven't noticed them. The light dynamo still works. 

If it's relevant, I'm talking about a simple Dutch style bike without any fancy parts. I only ride it on paved flat streets.
You are lucky to have V-brakes, because they make repairing the wheel yourself an easy half an hour task. Plus the tool is $2 usually.

Spokes pull the rim one way or the other (look at the spokes and their angle from the hub flange to the rim). If you tighten a spoke, it pulls the rim away. So, you 1) tighten your brakes barrel adjuster until they rub heavily 2) tighten the 2-3 spokes around the dent to pull the rim away 1/2 or 1/4 turn and loosen the the same amount the spokes, pulling the rim the other way 3) repeat many times, until there is nearly no rub 4) loosen the brake's barrel adjuster to the normal riding setting.

If you don't fix the wheel, it will be easier to get damaged the next time. That's it.