I totally concede with your comment on WB always pushing their actors for Oscar noms. It was something I was previously unfamiliar with.
Now to address your argument
To suggest that Halle Berry is a bigger star than Jennifer Lawrence is patently ridiculous. Berry may have better name recognition at the moment but that's not what matters in Hollywood. Lawrence can instantly get a film greenlit by just attaching her name...Berry could maybe get a cheap direct-to-dvd film greenlit with her name alone. Lawrence is almost a lock for her second Oscar nom this year while I will put money on it that Berry is not.
Firstly, Your using the term 'patently' incorrectly in your sentence.
Secondly, you just made my point for me. Halle is a bigger star because she has much better name recognition. In my Film Studies Class some time ago we were discussing how we categorise an actress as a star and though you are right that one of the deciding factors is getting a project greenlit just by attaching their name. (Though I don't believe Lawrence has that kind of power yet. She's only been in one smash hit movie) An even bigger factor is name recognition. In our class one of the students tried to suggest lawrence as a star but she only addressed her as 'that girl from the hunger games' when asked what her name was she said she didn't know. Our teacher then asked her how much star power she had if she did not know her name.
Whereas if I said Halle Berry, people would say 'Catwoman' or 'Bond Girl' or 'Storm' or 'Oscar. She has that recognition. Some people don't even know that Lawrence was nominated for an oscar for Winter's Bone. (which is an amazing film btw) Now back to my original point:
DoFP will need all the publicity it can get if it's to be a direct rival to Marvel and especially since it may be opening against Warner's the Hobbit.
But no matter how well they market it the film won't do as well if they don't have big stars to carry it. Fassbender, McAvoy and Lawrence have all had their profiles boosted since First Class but still are not bigger stars than Halle Berry
I still stand by this point. Before Warners would agree to pay for distribution rights for Cloud Atlas they wanted stars to carry the film. The wachowskis chose Tom Hanks and Halle Berry. She still has star power despite not appearing in any good films in a long time.
For X-Men If the posters have Halle's name and image it will garner some more interest. (In addition to the interest it will gather anyway for being an X-Men sequel. And a DoFP one at that.) I think Fox already knows this if youb refer to the posters for X2 and X3. Halle's image is always the most prominent after Hugh Jackman. She was the biggest female star in the franchise then and still is. Jennifer Lawrence still isn't a big enough name and looks practically unrecognisable under all that Mystique make-up anyway.
P.S. I wouldn't completely write off Halle Berry getting an oscar nom. Almost everyone seems to agree that she gives her strongest performance in a long time plus she's a previous oscar winner. I could see her getting nominated. And could see her getting a golden globe nod as well possibly a win, GG seems to

her.