At the same time, it makes smaller families even cheaper. I mean, I'm playing in Warsaw. It's 1952, but let's look aheda to 2020. I don't have a lot of juicy destinations that are beyond 2250NM. So, I'll have the choice between A320neos, at 160M$ per piece, or equivalent C919, at 80M$ piece. With less range and choice, but for such a difference, who cares?
Of course, someone playing in the small UK's airports, whose demand to the US airports is often around 100-150 might ignore completely the C919, and head towards the MAX7 and its kickass 4000 NM range. That's another market. But he'll pay far more for his airplanes - even the ones flying to Warsaw, against my far cheaper C919.....
What I like in this game is that you've got to make choices. You choose your niches. In this game, in Warsaw, I'll have medium and large. So small(I did swarm in Warsaw with metros, long ago, it's fun and efficient), and very large(for which demand is not impressive anyways) will be ignored. It's a risk : opposition could try to sneak into those niches, and steal important slots for that. But if there is no risk, there is no merit dominating the base.
EDIT : that being said, I made again the calculation when I went back to 2 fleet groups, and it was making my margin better by 3.5% - I'm around 35% of margin. It is a real difference, but not a game killer. At current company sizes, you can perfectly field several fleet groups and still be profitable. Optimizing for costs is not always the best choice. You just have to know WHY you are overspending in maintenance - opening new markets is usually a good reason to bite the bullet.
What I don't know is the effect it will have on very big companies. We can't measure that yet, and I probably won't with my small HQ in a small market.