Your numbers are off, because you are not considering overhead of support people who are not programmers. I think the assumption of "purely development" is a really bad one.
That was intentional to show an "at best" physical maximum.
I work at a Japanese company, so I'll use my numbers.
145 employees -
5% accounting - 7 people
4% IT - 6 people
2 Admin / receptionist - 2 people
3 HR people - 3 people
Way too many managers and directors - 15 people
Way too many executives - 7 people
4% Sales and Marketing - 6 people
People I probably forgot about - 4 people
Total not programmers: 50 people
This is probably the low end.
So now we're at 95 potential programmers, maximum. You're assuming that ~35% are working on Sword/Shield (50/145), so that's more like 33 programmers working on SnS. I am lumping artists and design people into programmers here.
Of those programmers, some are working on the engine, some are porting legacy code (as suggested), many are going to be artists and design people (doing pokemon, people, buildings, layouts, textures), some are working on terrain and maps, etc.
Of the number of potential people working in the area that you're complaining about, it's realistically like 2-5 people. And then they have other shit to do, besides your complaint.
My complaints are not limited to any specific area; the entirety of what we've seen from S&S shows low effort, corner cutting and overall lack of time. The graphics rival Nintendo 64 and Gamecube games, models rendering too late or disappearing, removal of Pokemon and dozens of features that they have removed over the years, including the recent Mega forms and Z-moves.
The game that Game Freak has shown thus far does not look like a game for Nintendo's latest flagship console. It does not look like the resources were provided to give the team the ability to do so. The game for the highest grossing media franchise in the world on the most powerful device the franchise has been on already reports the least amount of features from previous games.
Let's please be reasonable and not calling people lazy for trying to make a game, just because they didn't prioritize the one feature that is really important to YOU.
I reiterate; I have no complaints over any one feature; Game Freak has removed features and content since the move to 3D. Each game has given the players less and less, citing various reasons, and now here we are.