Looking at it from another perspective, I can see this being Game Freak's opportunity to jettison a lot of messy legacy.
Look at it this way. Aside from the Pokémon themselves, every mainline Pokémon game needs to provide:
- Rain/fog to evolve Sliggo
- Moss Rock to evolve Leafeon
- Ice Rock to evolve Glaceon
- Magnetic field to evolve Magnezone, Probopass and Vikavolt
- Icy mountain to evolve Crabominable
- Gyro check to evolve Malamar
- Deep-Sea Scale to evolve Gorebyss
- Deep-Sea Tooth to evolve Huntail
- Dragon Scale to evolve Kingdra
- Up-Grade to evolve Porygon2
- Dubious Disc to evolve Porygon-Z
- Electirizer to evolve Electivire
- King's Rock to evolve Slowking/Politoed
- Magmarizer to evolve Magmortar
- Metal Coat to evolve Steelix/Scizor
- Oval Stone to evolve Chansey (from Happiny)
- Prism Scale to evolve Milotic
- Protector to evolve Rhyperior
- Razor Claw to evolve Weavile
- Razor Fang to evolve Gliscor
- Reaper Cloth to evolve Dusknoir
- Sachet to evolve Aromatisse
- Whipped Dream to evolve Slurpuff
- 47 Mega Stones to use Mega Evolution
- 18 type-specific Z-Crystals
- 17 Pokémon-specific Z-Crystals
- Gracidea to form change Shaymin
- Red Orb to form change Groudon
- Blue Orb to form change Kyogre
- Griseous Orb to form change Giratina
- 17 Plates to type-change Arceus
- DNA Splicers to fuse Kyurem with Zekrom/Reshiram
- Reveal Glass to form change Tornadus, Thundurus and Landorus
- 4 Drives to type-change Genesect's Techno Blast
- Prison Bottle to form change Hoopa
- 4 Nectars to form change Oricorio
- 17 Memories to type-change Silvally
- N-Solarizer to fuse Necrozma and Solgaleo
- N-Lunarizer to fuse Necrozma and Lunala
- Pokémon Go connectivity to evolve Melmetal
I'm probably still missing some, but that's a full 151(!) items plus 6 in-game conditions.
All of these items/conditions have to be provided
in-game, usually through NPCs. It's actually insane how much cruft they created for themselves by introducing all of these quirky evolution methods.
Somehow they miraculously managed to provide all of these in Sun/Moon, but it was very painfully obvious that a lot of NPCs literally only existed just to give you this one item. It came off as very forced.
...having said all that, I'm still not happy with the decision to remove my ability to take out my Pokémon and use them when I choose to. The worst part is that Pokémon Home is only forwards-compatible, so all of the Pokémon I send there are essentially in indefinite cold storage (which I have to pay for).
So, my unpopular opinion is that I support Game Freak's decision to shave off the cruft and make the games they want to make, but they still need to acknowledge the legacy they've created for themselves.
Here's an idea for free, Game Freak:
Make a Pokémon game (or even put this into Home's Switch version) that is purely functional for training, breeding, trading and battling all 800+ Pokémon. No need for a world, a story or even updated models (you can upres the Sun/Moon ones).
You could have a small simulator room to recreate evolution conditions and a vending machine to provide the evolution/form change items. It doesn't need to be more complex than that.
That way the competitive scene could still be active, GF can balance their games based on a limited scope for each one, and I wouldn't feel like my Pokémon were rotting away in storage.