Campaign easter eggs
To make the game/story mode memorable they need to include unique and or crazy easter eggs in the story. Especially like how old games used to do it. Ones where we have to solve puzzles or it leads to new content or hidden customizables.
Incentive to play
Ow2 needs big incentive to play the story mode also. They need exclusive story skins, sprays etc to make us want to come back. They should add special dialogue in hidden areas or even multiple ways to finish a mission. ALso a time attack or competitive option for speed runners.
Mastery unlocks
This could easily be applied to pvp, but they should add special bundles (free ofc) which you buy with gold from lootboxes that unlock a miniature battle pass but for only that character. The more you play that character and gain xp with that character the more you unlock special skins etc from the mastery bundle. If you rememeber ‘Paragon’ on epic games had a similiar concept. you unlock the mastery skin which gave you a skin but not as cool, then when you played that character with the skin equipped you unlocked items, rewards and customizables, to eventually reach the skin you first got but animated and more flash.
Story
Latly, there should be a mark left once we finish the story. It should be worth while. there should be time and effort put into the story where we actually get attatched to characters and feel nostalgic when we hear the soundtrack to certain missions.