Long story short: the DLC remains at full price as a way of coaxing people to buy the GOTY.
I don't think that's EA's intention. It's making people not wanna buy the DLÇ, not forcing them to buy GOTY. It's just a flaw on marketing strategy, and the great marketers are too high to be reached and reasoned.
Some of you adviced me to buy GOTY Edition just like EA. I already have the game. I bought it years ago. I don't see why I am forced to buy the same game the second time.
At least they could add something like a "season pass" for people who bought deluxe edition. That way we could get DLCs free when they were released and since we paid for them in the very beginning, there would be no issue. A far better solution than "buy the game second time cause you know it's cheaper".
I will never understand how people can complain about the re-buying the game in the GOTY edition to get the DLC when doing so is still cheaper than buying the DLC piecemeal. It makes zero sense.
And why would somebody need to buy the same game twice?
Sadly, that's more common to happen than we'd expect. See Mega Drive and SNES games, that were sold in last years on Steam, Xbox, Wii, etc. We're not allowed to download roms and play them on public emulators if we don't have the cartridges, but if we do, we're allowed to buy them again to play on current hardware.
I accept the DLÇ business model. Instead of taking 3 years to develop a full game (and another 2 years to develop an expansion), and during that time keep eating money with no return and no assurance that the Return over Investment and the profit will be provided, developers have better time licensing Unity or Unread Engine and developing the minimum possible content to make it a game, and then sell it. If the main game succeeds, they take the profit and invest themselves on new content which is sold to feed more work. I'm ok with that and they have all my support on getting investments for game development.
But these DLÇs are breaking the market. Content that should be basic is being sold as DLC, there are DLC that have very little content, and as shown where we're urged to either buy everything 0-day or wait for years (which we'd wait anyway) for the GOTY edition. Not even softhouses' marketers are able to handle this mess.
On movies we're seeing the same. A plot that could me put in a 3h movie or shrinked for a 2h one is extended to a trilogy, and the middle movie gets boring and empty. Avatar had 3 editions, people who had bought the BD early had to buy it again to watch 10 extra minutes, then buy it AGAIN for a few more. Gravity was already out and a new edition with new sound was released. And never anybody who already bought the movie has discount on the new edition.
What I do is just not play the games at all. I wanted to play Fallout 4 and didn't buy it, and now ppl are complaining it's too simple, our choices have no effect on plot, and there are too many DLC with less content than fan-made mods. DAI, if I knew the game in 2014, I'd not buy it until its GOTY was out. DA2 I'll probably just play the main game and move on.