Malbim: Scientists say that it is dangerous to for one who was bitten or stricken by something, e.g. a rabid dog or snake, to see its form. The opposite applies to an affliction via Hashgachah. Moshe made a copper snake, and one who was bitten by a snake looked at it and lived. Through forms like the afflicters, they show that Hashem strikes and heals miraculously.