cut out stryker, rain and sheeva and put in Quan Chi, Shinnok and Kenshi. These three characters just need to be in this game.

And the other was Bo' Rai Cho....who was (and still is) anything but a popular and beloved character.
Li Mei was quite hated in MK:DA. I still remember the cries of "She's just a Mileena rip-off!" She didn't get good until Deception.

Bo Rai Cho had a key role in the storyline. Li Mei was not really relevant to the main story and it wasn't getting anywhere. Li Mei and Kenshi were brought back in deception due to popularity. I JUST KNOW many of those Mileena fans who cried about Li Mei being a Mileena clone actually mained her in MKDA. Then she returned in Deception and gained a new fanbase. I really think she wasn't a hated character until her Deception ending was revealed. And considering it wasn't even canon, i think it is lame how people complain and hate her for being a traitor while her ending didn't really "happen".

Well minus Shinnok because in my opinion, there might be two different sub-zero's in the game. It's hard for me to think that an enlightened Raiden wouldn't enlist the help of the younger Sub-Zero early in the game.