He WAS an important character. Then MK9 left him out.
My main problem is that NRS is undoing all the good work they did with MK9. The lore was too confusing and there were too many characters so they simplified it. They killed off Shao Kahn, Shang Tsung, and Noob Saibot for good. They put a bunch of other characters on a bus so they could bring them back or keep them gone as they wanted. MKX furthered this trend by killing off Mileena, Baraka, Sektor, Quan Chi, and presumably Shinnok. Sonya, Johnny, and Jax are set to retire whenever.
They reevaluated all the characters and put the focus on who they wanted. Sonya and Johnny are the main heroes, taken over by the Kombat Kids. Bo Rai Cho is a minor character who appears in one cutscene and gets his ass kicked, whereas Rain is possibly the most important character in MKX. It was his plan to steal the amulet, meaning almost everything that happens in the game happens because of him.
In the new timeline, Bo Rai Cho isn't important, Sektor is dead, Baraka is dead, and Smoke never got cyberized. Now all that is up for debate. NRS is doing the exact same crazy crap that led to them having to rewrite the entire timeline in the first place. Canonicity is going out the window. And before you say it's not canon, Rain and Kenshi being in MKX prove that DLC characters are canon.
It's boggling that they thought Bo Rai Cho was more important than Rain or Fujin, even Sareena would've been a better choice. Bo Rai Cho shows no fighting ability, Smoke has no reason to be a cyborg or leave the Netherrealm, and Baraka should be dead and buried. This is rewriting canon to make references to the old timeline, it's sacrificing the great stuff MK9 and MKX did and if it keeps up Mortal Kombat is eventually going to turn back into the mess that was Armegeddon.