But they gave you xp during the Reach campaign. If fact it was the fastest way to earn xp. They should have brought it back.
your not playing as your spartan IV so you dont get XP it wouldent make sense if you were playing as MC and got XP sent to your custom spartan without your Spartan doing a thing. MP has a story to. It made sense for reach because you played as your custom Spartan III. It doesn't for halo 4 because in the campaign you play as MC. Its the same as halo 3 you didn't get Xp from campaign for multiplayer. You see what im saying? Halo 4 is all story based.