To be honest I'm not even upset anymore. But it's taken a long time to get here...
I was frustrated during the ORAS Battle Frontier fiasco, and that was the first sign to me that things were going downhill. Then, SM was an absolute slog and I struggled to enjoy it. The constant railroading, shrinking post-game content, National Dex being removed, no Megas, no PSS, etc...I didn't want to admit it, but Pokemon was losing my investment for the very first time. I started to think of just putting the series down.
I saw Ultra as a chance for them to finish the 3DS era with a bang, and win me back...But we all know how that went down. It isn't half the game that BW2 was, and it didn't even fix the original game's issues like Emerald and Platinum did before it. I had been so accustomed to the enhanced versions being great that this was another big disappointment.
Let's GO made it painfully clear where their priorities lie. Another game set in Kanto, and it doesn't even follow a fresh storyline with new locales or anything. It exists solely to capitalize on the success of a mobile game. With that, on top of everything else, I lost interest in the future of the core series.
Ever since then I've been revisiting older games out of nostalgia, and funnily enough I still get a kick out of them. It's fun to go back, with a better understanding of the mechanics, puzzles, etc. and take it all on. Battle Frontier, PWT, White-Treehollow, everything. I even used that wiimfii thing to mess around with lost events, and build up a new collection of 'mons. It's been an absolute joy.
ORAS was the last game that I liked (for the most part), so I'm collecting all of my bros there, and leaving the future of the series behind...Sword/Shield is doing some things right, but removing more features and a swath of the Pokemon roster is a massive turnoff. Especially with how much more they can do on this console. It's strange. But at this point, I ain't even mad.