I'm not saying the 2.3L is expensive or couldn't be used by Ford versions. But I see Lincoln wanting to differentiate itself from Ford cousins as much as possible and letting Ford keep the 2.0L as the top engine.
If you use the 2.3L everywhere including Fusion, Escape, Edge, Explorer, etc. then you need some other exclusive engine for Lincoln.
I'm thinking you have this for Ford:
1.5L EB 2.0L EB 3.5L V6
And this for Lincoln:
2.0L EB 2.3L EB (MKC)
2.3L EB 3.7L V6 (MKZ)
Not sure where the 2.7L Nano fits in especially if it's NA.
It also sounded like the 2.3L was created for Lincoln specifically.