I’d say it highly depends on the title. Not all games age well, maybe most didn’t. Nostalgia is definitely a factor when it comes to enjoyment of some of these games. I never played Zelda The Minish Cap before and I still enjoy it now, but maybe part of it is generic nostalgia for GameBoy type games. I’d also say GBA games are often more accessible than even older (say NES) games.
And graphically, sure, newer games look quite a lot better. This game didn’t get the remake treatment (yet) though. I disagree that there has to be a “balance” between visual effects and gameplay though (aside from prioritizing development resources). A game can have both amazing graphics and great gameplay mechanics. I also think great graphics and visual design can enhance the gameplay experience.
But I don’t know, I still enjoy the odd “retro” game every now and then.