In economics this is called "price discrimination."
Basically imagine you have 100 potential customers for this product.
One group of 50 (we'll call them Group A) will only pay $700 for it; and if it is only $700, they are ok with a more limited set of features.
Another group of 25 people (Group B) will buy it for $700 with more limited features, but *would* pay $1000 for it with expanded features.
Another group of 25 people (Group C) will only buy it with expanded features, and they would pay $1000 for that.
If you sell it with limited features for $700, Group A will buy and group B will buy, and you will make $52,500 (75*700)
If you sell it with expanded features for $700, all 100 will buy, and you will make $70,000 (100*700)
If you sell it with expanded features for $1000, only Group B and C will buy, and you will make $50,000 (50*1000)
But what if there was a way to sell it with limited features for $700 and expanded features for $1000?
Now all 100 will buy and you make $85,000 (Group A: 50*700, Group B & C: 50*1000).
DLC allowed for price discrimination which maximizes your revenue in many cases. Companies love price discrimination but in many cases it is either impossible or illegal (i.e. a company could maximize their revenue if they charged a rich person $50 for a box of cereal but a poor person $5, but you can't do that both logistically or legally). But in situations where they can do it, they often will do it.