I get Havok. His role was pretty much the same as Quicksilver's in Age of Ultron. A death that motivates their sibling to be a hero.
Jubilee was meant to be nothing but a cameo. I can understand the other characters. Storm was the only that really needed to be in this movie due to what was set-up in DOFP.
I mean many people have forgotten major details about that film. Like Xavier holding back Jean's power because he believed she couldn't control it and Jean struggling with control of her power that resulted in Scott's death. The Jean/Xavier story in Apocalypse was meant to be a resolution to that, which many didn't caught.
I would have to disagree about the sentiments regarding Jubilee being nothing more than a cameo from the start. If you look at the cast list in the credits, she appears before Psylocke and Angel, even.
Also, if the deleted scenes with Jubilee were left in tact, Jubilee would have had more dialogue than the two of them combined.. Almost as much dialogue as Storm. I took the liberty of counting up Jubilee's dialogue and scene details:
Jubilee lines from X-Men: Apocalypse-
"Even the title, 'once and future king,' means the past defines the future." "We're the sum total of all of our experiences, so..."
"Uh um, Dr. McCoy, there's someone at the front door. She says she knows you."
"That was the library. The kitchen is in the other wing next to the dining area." "Eh, Yeah, three meals a day, snacks in the afternoon." "That sucks!" "Beverly Hills." "This is Scott, he's new here, too." "I got it." "Well there is one at 1, 4, and 7... But that is too late." "I still think Empire is the best. It's the most dynamic, and isn't afraid to end on a dark note."
Scenes-
Classroom
Mansion lawn with Hank and Scott
Mansion tour with Kurt/introduction with Scott, Jean, Kurt
Mall montage
After Return of the Jedi mall scene
Beginning of Quicksilver scene in Xavier's car
Xavier's car headed back after Quicksilver scene
Getting knocked out by Stryker's soldiers and waking up on lawn
On Mansion lawn next to Kurt when Jean and Magneto rebuild mansion
Jubilee's screentime in the theatrical cut, if I recall, is 1:06 (one minute six seconds,) without the total time from her deleted scenes. The deleted scenes add an obvious substantial time. Colossus' x2 role had less screen time, as did Kitty and Jubilee from the first two films. (Including deleted scenes.)
She was, it seems, originally meant as a supporting character like Iceman from X-Men 1.
She has more lines than Bishop, Sunspot, Warpath, Blink, Siryn, Colossus (all x movies minus deadpool), Jubilee (x1-3 combined,) kitty (x1 and 2 combined)...