One of the questions that I want to bring up is how come AGB can make fantastic games, such as pokemon, but the modern games we have today, which are 2D, have performance issues? (Keep in mind the AGB isn't the most powerful thing)
Poorly programmed games (or, games that chose to prioritize other stuff) have performance issues. Well-programmed games (or, games that prioritized performance) have better performance.
You seem to be saying that every game for the GBA outperforms every modern game, which is simply not true. There were plenty of poorly written games for the GBA, and there are plenty of well-written games today. That plus modern hardware means that we're doing stuff today that would be physically impossible on the GBA.
It's a bit like the people who say that today's music is terrible compared to music from [insert decade here]. A lot of that is selection bias
, because you don't remember the 95% of songs that were terrible from your favorite decade, and you're ignoring the good songs from today. You're comparing one of the most famous games of all time to games that you see on Steam, which isn't exactly an apples to apples comparison.
By the last paragraph, I want to ask, how far have we abstracted? Along with this, in terms of shading, do we really need all the power we have today to represent our stuff?
Sure, one of the "problems" is that we have so much more available at our fingertips. Want a particle system in your game? That's a one-liner. Want physics? Here's Box2D. Want lighting? Here you go. So it can be easy for developers to shove a bunch of stuff that they might not need into a game, without worrying too much about performance or the hardware they're running on. They might design it for their $5,000 hardcore gaming PC, and you'll have issues running it on your 5-year-old Android phone.
But I would argue that's a good thing for the most part. As a developer, I don't want to have to worry about which hardware I'm running on, and I don't care about all the hardware-specific hacks that I could take advantage of if I limited myself like that. I also don't want to reinvent the wheel every time I sit down at the computer, so all these libraries and frameworks are great for me.
That being said, there is a big community around developing games for retro systems. It sounds like you've taken an interest in that, and that's great. Have fun with it. But it's certainly not as simple as saying that the GBA is better at games than modern hardware and software.