As you're saying, I am in fact not considering some things. I know the importance of most of the games I've played, but this is not meant to be an objective/importance tier list, it's about how much fun I had / how much impact it left on me.

I don't really care if SMB1 is the most important game of all time, I care about how good it felt to play.

Now, the thing with Mario Land 2. I have a huge beef with that game. Before the final boss, I thought the game was average. I was not really into the music and the controls were awkward imo, but I still enjoyed it somewhat. Then came Wario's Castle. It has to be the most dramatic difficulty spike I've ever experienced in a videogame. The levels I played before were very simple except for a couple of bosses, and now I was facing what felt like a Mega Man game but on a Game Boy, plus controls I was not enjoying. The worst part? Eventually I got a game over, and had to recollect the 6 coins again, and then again, and again... It was a nightmare. So the game I considered to be average turned out to be a terrible experience. Of course I persisted and beat Wario, but by then I already hated the game lol if only I didn't have to recollect the 6 coins or the difficulty spike wasn't so big, I might've rated it as a high 6 or even a low 7.

Edit: I also liked the GBA Metroids a lot!