When it's DLC on release date, I hate that, why didn't they included the content in the disc ?
There's plenty of explanations. Most of them have the word business involved. It's the world we live in, dude.
Although some games give you content that IS on the disc. Stuff like Graces F. Half that DLC is stuff you can unlock by playing the game, or you can pay to not have to deal with the hassle. Or there's DLC like Record of Agarest War that just boosts your characters to Super Saiyan status. Rather than having to grind for it.