That's a ridiculous criteria. Any app can get a one star, it just takes one stupid person (I saw an app that was for tracking where you walked to help those of us who hike a lot see our trail get one starred cause the lady wanted it to tell her how to get somewhere in her car. She totally missed that the app was not for that and was furious that it wouldn't give her directions! I've seen stupid reviews where the person one starred the app cause it was a puzzle game and it had no action! They obviously didn't read the description. I see Asphalt 6 has a one star cause it has no girls <- it's a racing game. I've seen one star reviews cause the company dared put the app on sale and the people who missed the sale were bitter that they missed it).
It is kinda like ebay, if you sell a lot, you will eventually get one person who is unhappy and sometimes, that person is being stupid/unreasonable.
So to eliminate an app just cause one random person disliked it is kinda stupid. It doesn't mean the app is bad. In fact, if it has plenty of reviews and just one one star review, even if it is a valid review, I'd still say that speaks more in its favor than not.
I think you missed the point. I believe the point is that everybody is different. Apps that you love and need may be apps that I think suck (and hence I give a 1-star review to). Whereas apps you think suck or apps you don't care about may be very useful to me. If we eliminated all the apps you think suck, we may be eliminating many apps that I need or love. The advantage of such a big catalog is that while maybe everyone agrees there are 500 good apps, those 500 are not the same for everyone.