Zeromus wrote an incredibly long article so I'll summarize the most significant points that I'll be responding to below. These are his thoughts. My opinion will be farther down after the summary.
Workers mining minerals currently drop in efficiency starting at the 17th worker. Due to the maximum supply cap, this generally leads to a hard cap of 3-4 currently mining bases as more than that cuts into your army supply.
He says that this is an issue because it doesn't reward map control as much and tends to favor deathball style play.
The article then talks about a few different ways to reduce the scaling of workers (decreased efficiency in smaller numbers) while compensating the workers in other ways to maintain an economy that is very similar to what we have so far in most parts of the game, but will reward spreading workers out over a greater number of bases for a greater economy.
The basic premise is that if workers become less efficient in smaller numbers (~8-9) then you get a greater mineral income by spreading workers out over more bases.
He talks about a few methods that he considered and contemplated. The final proposed method of implementation is called the 'double harvest' model. This model makes workers less efficient starting at the 9th worker by tweaking the worker's ai. In addition, workers would also mine twice as long and for twice as much which increases the income of a single worker as it reduces travel time.
The author claims that a major upside to double harvesting is that it rewards players for expanding and does not punish players for not expanding, which is a current feature of the LoTV economy. If you don't expand in LoTV, you run out of money very quickly and are not able to do more things. In the double harvesting model you run out of money slower and so are punished less for not expanding as much as your opponent.
Now for my thoughts.
Too many workers cutting into army supply is because of when players tend to max out given the current rate of harvesting and amount of money available per base. When players get to ~65-80 workers they are also able to quickly reach the maximum army supply so additional workers would cut into that amount. So far this is not an issue in LoTV due to decreased minerals. Players rarely hit 200 supply and if they do, they are not at 200 supply for very long. Even if they are, players are usually unable to re-max to 200 supply immediately due to general lack of money. When I feel like I have too many workers in LoTV, it is because I don't have enough bases to use them effectively and not because my army is too small.
Due to the reduced amount of money available at each base, it becomes much harder to max and stay maxed. In most LoTV games, players will max at most 1-3 times over the course of the game and will generally be fighting in the midgame with ~120-170 supply. The primary reason that it's not viable in HoTS to go above 3 mining bases worth of workers is because that is when you max and those workers could be army supply. In the LoTV economy, this is rarely an issue because of how few resources there are. The 3 base mining cap is a myth in LoTV and additional time will show that additional workers and bases will be useful.
The cap on having ~3 mining bases just doesn't feel true in LoTV due to the reduced resources in the game. Shortly after you get 3 mining bases, you need to take an additional one as you have reduced efficiency in the bases already up as mineral patches run out. While you rarely see people in LoTV going up to 4+ mining bases at the same time it has more to do with bases mining out so quickly rather than not wanting to to make enough workers.
The author has a section regarding 'strategic diversity' and how it must be maintained. He says that the LoTV economy will kill ultra defensive/passive styles of play. This is a good thing. Just because some strategy can exist in the game, doesn't mean it should. There is little argument that protoss deathball, swarmhost turtle, and raven mech are generally bad for the game. They lead to relatively non-interactive situations that often drag on longer than needed. More options does not mean a better game. Passive and ultra defensive play have been some of the most boring and terrible games to play as well as to watch. Seeing these types of strategies go is a good thing for Starcraft as a whole.
He claims that the LoTV economy removes hyper defensive play and makes expanding a necessity rather than an option. It's far too early in the game's life span to make conclusions like that. There simply hasn't been enough time and eyes on the game. Even if this statement were true, the best part of Starcraft is the conflict and battles. We can appreciate the technical skill of being able to macro for a long period of time flawlessly, but the best part of the game is to fight each other. A change that encourages a greater number of expansions while reducing hyper defensive play is a positive one as expanding more and forcing people off their side of the map will help promote conflict.
There has also been some discussion regarding the 'lost start' of the game. With 12 workers, many old builds no longer exist, or exist in some brand new form. This change is another example of Starcraft trimming unnecessary parts of the game in order to more fully focus on what's most important. Starcraft is not a game about making 1 worker at a time and watching them mine for ~2 minutes. Starcraft is a game about fighting, taking map control and maneuvering an army while making strategic decisions regarding tech, macro and expansions. Regardless of what is lost from the start of the game, there is so much more that is gained by creating a game that starts closer to what is most important, which is the actual fighting and back and forth that makes Starcraft so exciting.
Overall, the LoTV economy is a change in the right direction. While I am not convinced that some of Zeromus's ideas are necessarily bad, I do disagree on a number of points and favor the current LoTV economy more than others. That said, it's a long beta and there's plenty of time to try different ideas.