My unpopular opinion is that DLC is not, in and of itself, bad. If you don't want it, don't buy it! If you do want it - great, no problem! In a world without DLC, you either have to buy the whole game, or not. If you tried it and didn't like it, you have wasted the whole price of the game. Whereas in a DLC system, you've spent the price of the base game, but that's effectively just a fraction of the total game price. You risked less.
What is a problem - and what I think most people who think they're mad about DLC are actually mad about - is charging a price that isn't commensurate with the amount of content you get. If a full game is "worth" $60, and it's split up into a $20 base game and 4 $10 DLCs - great, everyone is (or, should be!) happy. But if the publisher charges $60 for $20-worth of base game and then charges for DLC on top, you should be pissed - but you should still be pissed about that mispricing even if the DLC didn't exist. Yes, DLC is the reason why that pricing strategy is adopted - but that doesn't mean that DLC itself is inherently bad. There are possible implementations that are not flawed.