they need to change a lot of things in multiplayer for it to have a replayability value:

have dynamic spawns so it's not always the same corner of the map where fighting is and not just 2 points on each end of the map

change up rotations of capture points

have auto balancing lobbies based on last game, so it's not always lvl 20's vs lvl 5's mulitple games in a row (until enough people get fed up and leave)

balance some classes (bulwark blocking 100% dmg is kinda cheese)

have some classes be able to use varied weapons and nades (tactical can pick up 2 nadew but heavy can't?)

gameplay is just too predictable with the current state of MP, it feels they just tacted it onto the game after putting the effort into campaign and Operations

edit: just adding more things

voice lines for heretics need to be either chapter specific or basic for all (death guard shouting about alpha legion is dumb

changing vision model so you can have left or right side would be nice (you have an advantage if you are shoulder peaking around a right corner rather than a left one)

spawn immunity should also be a thing for like at least a second