The poll doesn't quite answer my overall thoughts on this.
Mario Kart 8 Deluxe is a complete package and a great base game but its DLC is a half-assed amalgamation of Mario Kart Tour content that has a heavy style clash with the rest of the game. It is no way as polished as the DLC tracks we got in the Wii U version of Mario Kart 8 (which also came with new vehicles), and thus I found it a gigantic let down, especially considering how Mario Kart 8 Deluxe sold 60 million copies and was a far more successful game than the base 8U. Mario + Rabbids Sparks of Hope is also a complete package if I can recall correctly but also suffered disappointing DLC (I'm looking at the Rayman "crossover" specifically). Same with Super Mario Odyssey, has very mid DLC, but in this case, as opposed to the other games, I think it's fine. The post-game is repetitive and scant and I don't think every game needs like, paying extra for additional levels or whatever, it's fine for what it is.
Mario Strikers Battle League, Mario Tennis Aces, and Mario Golf Super Rush had very half-assed launches with a dripfed of content (like hooray Bowser fucking Jr. got added as a playable character, a character who should have been in the base bloody launch game to begin with) and that dripfed also tend to be very half-assed too. I'm honestly sick of Nintendo releasing their products that are skeletal at launch and then gets content that was cut out to add later (hello Alarmo, hello Virtual Console, hello Nintendo Music), it's very scummy and it's a way you can kill hype for the game early, and it's a way for them to manufacture discussion about their product. Hell, Sakurai I believe wrote in a video of his talking about how games launched in a bare minimum state is one of the absolute worst things you can do to a game, because first impressions are key and people will likely just drop a game and not come back to it.
Sure that DLC is free but I'm more cynical: I think it's cut content masquerading as free content.