I don't think the complaint here is about the size of the game. It's primarily about the limitations of the new Switch 2 console, or more specifically, the cartridges. 64GB max cartridge size is kind of a huge design fail, especially when the result is that you have to install these massive games on a 256GB console (which is another design fail).
Let's be real though; the developers could have put some effort into reducing the size of the game for the switch. The switch will not be playing this game in 4K, and most-likely would not suffer from some compressing to bring the game down to the 64GB limit.
So let's now get to the real reason for the choice: money. The studio didn't want to spend time and money to do a good job compressing the game down to size, nor did they want to pay for 64GB cartridges for the release. Any other reason provided is just PR fluff. You are not getting a better experience because of this decision, don't kid yourself. The only reason is more $$$ per sale.