I agree they are not entirely fair. However lottery/random systems have a lot of burden of work that ends up wasted, leading employers to shy away from doing it. If you have do X amount of paperwork per candidate and there is only a 20% chance of getting through to the lottery, why do it?

In the absence of enough funding and employees at USCIS to be able to individually assess people, having some kind of cutoff criteria is better than a lottery. Don't let perfect be the enemy of the good.