You really should double check that, because apart from having an emulator on a PC or console, you are not legally allowed to play officially licensed games on it under any circumstances. There really is no exception to this.
In addition, the copyright is valid for 70 years, so also for GameCube and Wii games there is still a limitation that you may not play them illegally.
The fact that many people, like you, don’t care about that and just copy or download those games, doesn’t change that. If you shoplift something, it’s suddenly illegal because you’re joking about the fact that you have to pay for it. And these few euros in special copy tax that we pay data carriers are, of course, nothing compared to the cost loss the company incurs if people just start emulating games.
And that last thing you say doesn’t make any sense. So, because you want to play old games on the current console if necessary, the company should only offer them for €1, otherwise you would be playing them illegally? The world is upside down, of course. It’s not about what you or anyone want, it’s about what’s legal. This does not and never will include playing 3DS, GameCube, Wii, Wii U and Switch games on the Steam Deck.
By the way, I totally agree with you about the exorbitant prices for old games (I also think the prices for new ones, but that doesn’t matter), but of course that’s another story and not really an excuse to go pirate. ..