On the one hand, I don't count the cosmetic things like unit packs, flag packs, portrait packs DLC. Yes, it takes time and effort to make, but most companies don't charge for cosmetic stuff in the first place unless they are a free to play model. Those that do get a raised eyebrow and a mention about horse armour.
The stuff that actually extends the functionality of the game, fine. But even then, their development model is pretty unique. They win a lot of kudos for after sales support, and I can see both sides to that.
On the one hand, it's all paid for. It's about $15 worth of content every 6 months, so you might as well be paying a quasi-subscription fee if you're into it.
On the other hand, if you're not buying the DLC, you get free patches that include parts of the functionality to support the DLC. It's kind of weird in practice - They changed a bunch of stuff in CK2's latest expansion, Conclave. I don't have it, but as part of it they've now introduced pacts. So instead of only getting alliances, there are non aggression pacts and defensive pacts. But when I am playing as a child, I can select the new education focuses and it has all the tooltips and such, but the whole thing does nothing, because that's a Conclave exclusive feature. When there are about a dozen expansions that you can freely turn on or off, avoiding interdependencies must be a nightmare, and it's all done in the name of allowing each part to be sold off piecemeal.
At some point you'd think it would be simpler to package it all together and either go subscription, or one price for life.