I suspect that reviews will drop significantly once people get their hands on the original Switch's version, seeing how that's the version more people will actually play.

$20 million isn't that little when you consider how short Pokemon game dev times are and how many staff FTE exist at GF. 

Suppose that the average employee who touches the game works on 10th Gen Pokémon for about 1.5 years (makes sense for a 3- 4 year dev cycle between main gen releases.) And let's assume the average labor cost per employee is ~$50,000 (+40% average Japanese salary of around $35,200 USD.)  

That would be $75,000 per employee for the game. At ~200 employees  about $15 million dollars. 

But realistically we would probably have to estimate only something like 60-80% of GF employees touch the game sufficiently.

That's about $9 million - $12 million. 

Labor is the overwhelming bulk of the non-marketing cost of developing a game.

Now if they spent an average of 3-5 years FTE on the game, it would approximate the typical game budget of an AA title $27 million - $60 million labor costs. 

Or Game Freak could double in size, but in aging Japan that is easier said than done. 

Or Game Freak could outsource a lot of work to vendors or other development studios, and we're seeing some of that with leveraging Monolith. 

The real problem is that a mainline Pokemon game should probably have a 5-6 year dev cycle rather than a 3-4 year dev cycle. But given that most of the profits come from merchandising that depends on more rapid releases, I don't think we'll see that. 

Edit: Comparing to American studios or studios with a lot of American staff of similar size probably isn't realistic because labor costs are likely double in the U.S what they are in Japan (mainly because of low inflation in Japan since the lost decade.) 

For Pokemon Sword:

Full production began in September 2017. Approximately 1,000 people from multiple companies were involved in the development, marketing, localization, and public relations. Around 200 Game Freak employees worked directly on the games, while about 100 Creatures Inc. employees worked on 3D modeling. An additional 100 worked on debugging and game testing

https://www.polygon.com/interviews/2019/10/24/20929597/game-freak-explains-the-1000-staff-missing-creatures-and-leek-size-of-pokemon-sword-and-shield/

For 400 full time employees across QA, developing and modeling for 18 months is already close to 30 million, even if they are on average paying as low as 50k USD yearly 

Don't know how they managed to keep mainline budgets around 20 million. My only theory is some of their development is outsourced, and they are hiring the cheapest labour they can possibly find

Marketing budgets tend to be separate from game development budgets, from what I can tell. The 20 million number is just for game development it seems most people are assuming.  Also "being involved in one capacity or another" is very different from spending a dedicated 3 FTE of capacity per employee (three year's worth of work.) 

Ohmori explains 

"Ohmori: Yes, it’s really just everyone who collaborated on the project including contractors, outsourced companies, our partners like The Pokémon Company, Pokémon Company International, Creatures, and all the other people that have been involved at any point in the development."

It's possible that some of this is falling under shared budgets or different budgets. Like I am sure there is some alignment between the game development and the merchandising parts of The Pokémon Company, especially when it comes to things like Pokémon designs, as an example. 

Given how these projects work, my guess is that any individual full-time employee likely is using most of their capacity on this game for about two years (probably at something like a 80% dedicated to this : 20% to other projects) at any given time then they move on to the next project as their primary. When that takes place, depends on the specific role, but there is almost certainly pipelining of capacity, and shared resources between different titles as one game finishes up development and the other starts. 

In the interview you shared, Masuda says this, 

Which I think is pretty fair for a transition from the 3DS -> Switch. That's roughly what we saw between 6th -> 7th Generation for home consoles, a 50% increase in staffing initially and then further increases as the generation progressed. 

Come on, try to understand them, it's not like these games sell like 20M+ copies, basically never have price drops and are supposedly from the highest grossing media franchise ever... oh, wait

Fingers cross that Beast of Reincarnation delivers. It looks like a mix of Princess Mononoke and Nier Automata. It would also show that Game Freak can handle more ambitious games.

They failed hard with Little Town Hero, and that was a passion project of theirs with probably even a smaller budget than any Pokémon game.

If they can't produce a decent small/mid-range game of their own, I doubt they can pull off a decent big project.

I don't think budget is the problem, at least not completely.

There are plenty of games with modest budgets that look great; Clair Oscur, Hellblade 1, Bright Memory Infinite, Plague Tale, many of Nintendo's own games, etc.

Even though those budgets do not seem high in comparison, we do not know the definition of what those budgets entail.
e.g. Do they include Creatures Inc. work on the pokomon or licensing the designs from them? Do they include work done by Nintendo subsidiaries like Mario Club or the localization hubs?
We don't really have enough info to say how much is the real total cost to make them, since the leak was GameFreak only I believe.

Good to see that the dev cycles increase from 3 to 4 years for the mainline series it seems. Weird to say I'm happy with longer def cycles, but they needed it.

Its Nintendo or its not. There is no ‘proper’.