But it comes down to this:
Let's assume a ref's ability is quantifiable and is rated out of a 100. Let's assume there are 50 FIFA-certified refs who meet the minimum requirements and standards, which for the purpose of this point is 80/100, any of whom are qualified to officiate in the WC. I don't know any hard numbers for this, so let's continue assuming, and say that these refs come from 30 different nationalities/federations, and there are 20 spots in the tournament. If Country A has 20 refs represented, all of whom rate 95 or above, for whatever reasons. The other 30 refs, from 29 nationalities, all range between 80 and 100, with most of them being in the 80s. The way FIFA works would mean that you're guaranteed to have several refs in the tournie, who score lower than their counterparts, but feature anyway, which essentially means a lower standard of refereeing.
You can say that so long as they meet the minimum requirements, it doesn't matter, but it does, just like you can have your meal cooked by someone who makes you an OK dish or an amazing dish, both of which are good enough to be served.
I know, this is a hypothetical that takes a lot of liberties, but this is the point we're trying to make. The World Cup should have the highest standard of officiating possible, and I'd rather have that than diversity. I mean, the refs nationalities was one of the first filters. Out of all the English managers who meet the standards, Webb was selected, and the same goes for every nation.
I appreciate what they're trying to do, but considering that I just want to watch some good football, I don't support it.