I don't think DOFP had a clear storyline going for it either.
Seemed clear to me. End the Sentinel program.
In the beginning, what was Xavier's motivation for being a drunk?
Raven left him, then his students. He lost his family, his cause, and his powers.
What's Magento's motivation for killing Mystique? All he had to do was get her out of the situation, and boom- they don't have her DNA.
In his mind, she would never stop until Trask was dead. He thought that he knew her better than Xavier did.
More than anything else, you already have 2 movies(or 3) that have absolutely no mention of the Super Sentinals yet being set far in future of this one. If they green-lighted this Sentinal program, it surely would have put into place after the first X-men movie.
In the comics, the Sentinels were created in the 1960's. Days of Future Past came out in the 1980's. The Sentinels weren't a constant threat to the X-Men, they just showed up every few years to give them trouble. It's believable that the Sentinels in the movie universe also took decades before being able to become the world conquering threat that they became in DOFP. We're talking about the Sentinels not appearing in three movies. We've had a thousand X-Men comics that had no mention of the Sentinels.
How was Mystique even alive for X1 X2?
I thought that they said she'd been captured and studied and tortured. I didn't know that they'd said she'd been killed.
They basically sacrificed First Class to include Hugh Jackman and Wolverine.
The main characters from First Class are still intact. Hopefully the next movie will introduce a young Scott, Jean, and Storm to the team.