Yeah but Ratchet and Clank Up Your Arsenal was awesome and it had both. It would help with the value and replayability of the game. Hell GoT added multiplayer after the fact and no one even expected it.
Rift Apart is on a completely different level than Up Your Arsenal though.
The traversal/movement, dimensional rifts, seamless transition from cutscene to gameplay, even the smoothness of the UI from opening up the weapons vendor, are great strides for the franchise. That's not even mentioning additions like the open world sections or side areas, the amount of NPC's that make the cities feel more vibrant, the introduction of glitches, or even the return of the battle arena! Personally, I'm hoping for a more extensive arsenal of weapons, maybe even more unlockable weapons for NG+, which would make a second playthrough even better.