Emob78: Sure, expansion content has always existed. Difference being is that we didn't always pay for it.
StingingVelvet: Uh... I always paid for it. I honestly have no idea what you're talking about.
Yes some games released small additions for free, but paid expansions have existed for decades on PC. Tales of the Sword Coast, Tribunal, all those level packs for Duke Nukem or Quake. DLC is just the same thing, usually smaller but still worthwhile when we're talking about "real" DLC, not stupid pre-order items.
I don't play Total War so I can't comment on that, but you're speaking in all-encompassing terms about all DLC. The ones I buy, dozens now, aren't any different from buying any of the expansion packs I listed above.
Ok, let me explain a little more clearly. Content used to be created and passed on through the brand by the developer... without cost. This was before the conquest by the known franchises that dominate the market now, like the Total War series, Assassins' Creed, Far Cry, Crysis, etc. Games used to be more open source in nature, in that if new content was created for an existing franchise, the content was filtered to consumers either free or via entirely new games in a series... we call them sequels. Now this idea of content infusion is done by the DLC/micro pay model, where you HAVE TO PAY for each new item/level/character/ending. That's the difference. Devs creating new content for an existing brand used to be on the level of mods or user based content. Now it's a totally separate and corporate model with its own payment structure/QA/time tables and everything else an entire game might have.
DLC went from bad idea to test run to industry standard in less than 10 years. I'm not sure how long you've been playing games, so when you say that you've always paid for DLC, it could be because you weren't playing games before you had to. I'm not making an accusation, I'm just trying to let you know that there was a time... long ago in a galaxy far, far away, where devs would release content for their games and no one had to pay for it. And if we did have to pay for it, it was because there was so much new content that they would repackage the whole thing and call it a sequel. Just tossing in some new armor for Batman to wear in the Arkham series is not a sequel, it's DLC.