Not really. The prices didn't go up until the second generation of Xbox and third generation of Playstation consoles. When Did Games Change to $60? - A Comprehensive Look at the History and Future of Game Pricing - 33rd Square
That's true in some cases and not true in others. As far back as Wing Commander 2 (at least) you could buy additional content for games; it just wasn't downloadable yet because Internet speeds and access wasn't available. Wing Commander 2 had paid expansions and speech packs. This was in 1991. Going farther back, some Japanese games had paid expansions in the 1980s. The only difference between these things and DLC is that you had to buy them on disks.
Notably, even today some games ship with free DLC, akin to the map packs you mentioned companies giving away. That kind of freebie is usually smaller and cosmetic, but it still exists, and in some cases better DLC is given away free.
I probably shouldn't even address this one as no one ever changes their mind on it, but I consider this more of a faux pas than an actual problem, as long as the company is clear and truthful up front about what you get when you purchase the game and what you have to pay extra for. If you buy a game for $X, knowing that DLC is not part of the price, then whether it's on the disc or not, the company delivered what it promised. It's not much different from going to a restaurant, ordering a meal with a regular drink and regular fries. Yes, they have more fries waiting there. Yes, they could have put them on your plate. But you didn't pay for them, so you didn't get them. (The obvious difference is that food has a material cost and once the DLC is made, they can provide it infinitely, but it still isn't free to make. Designers, programmers, and artists cost money. Recall above where I pointed out that games cost $50 in 1995 and $50 in 1995 money is $103.45 today. DLC absolutely can feed corporate greed, but it's also one of the things allowing game prices to rise slower than inflation.)
Don't get me wrong; some DLC is absolutely a cash grab and is shameful, and some is an honest purchase with a bad price. Everyone likes to point at Oblivion's horse armor DLC, but it was completely optional, had no gameplay effect, and it was the literal first console DLC; the pricing was basically a guess.
Other DLC though represents a lot of time and money invested, and significantly increases the value of a game. Borderlands 2's Mr. Torgue's Campaign of Carnage added hours of really good gameplay and frankly hilarious voice work to the game. Its Tiny Tina's Assault on Dragon Keep was amazing, and later got a standalone release. I've never felt like I got a bad deal out of an expansion to a Civilization game, and those are DLC, and Phantom Liberty was AMAZING DLC for Cyberpunk 2077—and CD Projekt Red backported their general gameplay changes developed for Phantom Liberty so even people who didn't buy the DLC got major upgrades to the game.
I'm running very long here. All I'm trying to say is that what people curse as DLC existed long before what we call DLC, and sometimes it's worth every penny. Game prices went up because ALL prices go up over time. Games just do a much better job of holding a fixed price, so when the price does go up, it feels like a huge jump.
Edit: Geez, I got up at 4 am because I forgot to pay rent and needed to do it immediately, and look what happened. I apologize if any of the above could've been better phrased; I am writing it at 4:45 in the morning, after having been asleep. >_<