A blogger here wrote a column that I found to be quite disturbing.
It shows some people still work under the assumption that a market with only a few competitors is a bad thing.
Some legislators and Congress critters look at states where Blue Cross is the dominant player and state categorically that this is bad for consumers. In their small minds, market domination by only one, or a few companies, is prima facie evidence that the government need to manipulate the market in order to introduce new players which will in turn drive down prices.
It never occurs to them that Blue Cross (or whoever) is dominant because they have lower rates and/or better value.
Or one might argue that lower rates (or better value) led to market domination.
Regardless, in a free market in which prices are not manipulated by government intervention, consumers will decide who offers the best value which usually means the lowest price.
If one or more carriers dominate a market based on price it will be virtually impossible for a new carrier to come in and make a dent in market share unless the dominant carrier makes a conscious decision (through pricing) to allow new players to usurp their market share.
Competition is a good thing, but unless you put on your tin foil hat and believe there is collusion among the players to "fix" prices it is ultimately the consumer, not the carrier, that decides the competitive base.