We only know this stuff because they wrote it that way. Why would Scott and Jean be any different? We don't know how they met or how they discovered the powers they have. How is that somehow less interesting?
Well, we do see some backstory on Jean in X3 and on Cyclops in XMO:Wolverine. Even if those films are officially disregarded, then the audience remembers things.
I'm not saying it wouldn't be great at some point to see them at the school - and I'm sure they're debating when to put them into this franchise - but I don't see the point of rushing in everyone that was there at the start of X1.
I also don't see how following the comics more precisely would necessarily be better.
Marvel itself doesn't follow the comics. The first Avengers were Iron Man, Ant-Man, Wasp and Thor, who inadvertently answered a call to stop the Hulk (who was on a Loki-controlled rampage). No SHIELD, no Nick Fury, no Captain America, no Hawkeye, no Black Widow, no alien army, no Maria Hill.
Captain America joined the Avengers in issue 4, after being found in ice during a battle between the Avengers and Namor. Hawkeye joined in issue 16 along with Scarlet Witch and Quicksilver, after everyone else but Captain America resigned. Black Widow first encountered the Avengers in issue 29 - and as an opponent, not an ally. She begins to fight with the Avengers in issue 36 but doesn't become a member for years.
The Avengers film doesn't follow any of that. None of it.
So let's get real here regarding comic book accuracy.