I bought a physical copy of an EA game and was forced to sign in to Origin

Origin is used as a way of registering and maintaining EA's more recent games.

The benefit for you is that it will patch your game for you and notify you of any new content. It also serves as a place to keep all of your digital games together although in the case of Origin the stores limited to EA games and a few others.

The benefits for EA are that they can advertise to you each time you go to launch one of their games and they can use it as a form of DRM.

Basically you have to use Origin because EA decided that you need to use Origin for that game. Their product their rules.

It will say on the back of the box that Origin and an internet connection are required.

If you prefer to buy DRM free games that do not require launcher applications then you might want to look at sites like good old games. You will find however that most big companies will tie their products to a particular store app.

Origin is required to play any EA game.

Much like any Steam game, Steam is required to play them. This "environment" is required to download any new content or updates for games you play.