As for me, I felt the exploration was the weakest aspect of the game, as you have two Galar Mines, and a pretty cool mystical forest, and that's about it. I think the Crowned Tundra will increase this aspect more than the Isle of Armor already has by not only being more diverse than the wild area, but having different landmarks to explore for Regis and whatnot.
I have the feeling there were going to be full-fledged dungeons in the game, but it was an early thing to go in the chopping block. The reason for this is that there is a power plant in Route 3 that Sonia speaks about, and there's a roped-off path that leads there, but it's never mentioned again, and you can never reach the building. Historically, after caves and forests, the third most common dungeon theme in Pokémon games are industrial buildings. The way I see it, that was likely going to be a dungeon with a plot point, possibly with Team Yell admins (which I would say, well, is a missed opportunity, as Team Yell is the first adversarial team you fight without admins--even Aether Foundation had one in Faba).
On the Galar region map, to the very West of the Wild Area (where there's just a cliff wall in the actual game), there's an area beyond a railway bridge that looks like it could've been a little beach where you could catch the likes of Krabby or Wingull, and could lead toward a little bit of sea where you can surf around and catch marine Pokemon. It's a shame there weren't more sea routes in the game other than Route 9, and a bit of the Wild Area with a beach that leads to a sea would've been great. I mean it would've made more sense than Wailmer just being in a little land-locked pond far away from the sea (how did it get there?).
I've noticed that too, and I suspect that was originally going to be a seaside section of the Wild Area that was ultimately cut.
Something else on the hand-drawn Galar map: There is what appears to be a dead volcano to the northeast of Hammerlocke. It's on the eastern end of the gigantic cliff walls. That honestly looks like a major battle would've taken place there, though I couldn't tell you what it could've been. In addition, there appears to be a hole in the middle of the cliffs at ground level that you could walk into. Considering it's a hop skip and jump to Wyndon, this may have originally been Galar's Victory Road.
And while it did make the final game, the Wyndon Eye (or whatever it would've been called) serves no purpose. Considering its location, this may have been some alternate battling facility to Battle Tower.
Honestly I don't think they are hard but I found it had actually strategy with the Totems and smart AI/good movepools. I do think they're the most difficult games but not by a significant margin.
Besides the first-generation games, when Game Freak still had to learn how to control their own games' difficulty, it's Genius Sonority who's in charge of the tougher Pokémon games. The Orre games definitely felt a step up in difficulty, but at the cost of befuddling people who passed on the handheld Nintendo systems and went straight to Pokémon Colosseum or Gale of Darkness as their first games. Of course, Genius Sonority is now relegated to mobile Pokémon games when they're not making Denpa Men games.
I think that's the important takeaway here: Pokémon games, especially main series games, will be many people's first Pokémon game, many people's first RPG, and many people's first video game. I think that's the implication with what Masuda said. These are the people most likely to get frustrated and stop playing.
The precursor to the Just Dance games, for instance, was Boogie for the Wii. It was a HOT seller, yet the game practically plays itself--despite it being a rhythm game where you move the Wii Remote to the directions of the arrows, Boogie didn't care what direction y0u moved the remote or even if you're moving it outside of the rhythmic cues. It cared only if you were moving the Wii Remote at all when the prompt took place. It was very popular among people holding parties, where those who had never touched a video game before could kick butt, or at least feel like they kick butt! The same criticisms for the Pokémon series' difficulty could also apply to Boogie, and the critics tore the game apart for those very same reasons, but Boogie wasn't aimed at the sort of people who read video game reviews, and in a sense, neither are the Pokémon main series games. Both are designed to allow beginners to feel like champs, though Pokémon does still require you at least pay attention to what's going on, unlike Boogie.