Mmh I bought the Dead Space Bundle and what I received is keys for Origin so I don't know where you got that from.
I thought you also got installer downloads. So Origin wouldn't be required?
Depends on what you mean here. We're gonna get technical here.
In the beginning - EADM (EA Download Manager), which was later re-branded to Origin - was often an optional service.
If you bought a game at retail or for download from somewhere other than EA, you could just download the game from wherever you bought it from. Never had to deal w/ EADM/Origin, if you didn't want to.
It was an extra option - and if you wanted to, you could download EADM/Origin program from EA.
Later on, this changed. If you wanted to, you could take your key you got from somewhere else (Direct2Drive, Amazon DVG, etc) and then optionally activate a game over Origin.
Though, most games back then, you could run the game w/out Origin ever going/running in the background.
Origin program is now REQUIRED to download, install, and run in the background to run many of those recent EA-published games that were released AFTER
About Dead Space 1 & 2 - that's before BF3. After you've download, activated, and installed it - you do NOT need Origin running in the background while you're running the game.
Though, it is probably best you activate the key up over Origin; let Origin do the download and install for those games - just easier and more painless that way, normally.
It's just easier that way to let Origin do everything for you, for any EA-published products - especially b/c installs for games specifically from them are easy and streamlined. You don't ever need to back-up your original installer-files (like say GOG) or let it compress any special game files (Steam, Impulse/GameStop PC App). With EA-published games from Origin - you can just copy your actual installed game-folder elsewhere (for back-up - like on a DVDs, BR discs, another HDD, whatever).
For reinstalls - just copy and paste that actual game folder to where you want it to go on the HDD; and always just run the EXE file that's within the "INSTALLER" folder.