The problem goes far beyond just Game Freak, it's all parties, (The Pokemon Company, Creatures Inc., Nintendo). But The Pokemon Company in particular. The Pokemon brand has become such a giant, interconnected machine that when one cog breaks down, it impacts the entire thing, this is ESPECIALLY true for the games. While the mainline games themselves are far from the biggest money making aspect of Pokemon, it is without question the most important aspect. Every time a new set of games launch, it's not just the games themselves, it's every other aspect of the brand that goes along with them: Merchandise, the trading card game, the anime, movies, the spin off games, official fan events or marketing events, etc. The term "New Generation of Pokemon" isn't just a fancy marketing slang, it's legitimate. They are so tied together and interconnected and co-reliant that one setback, especially if that setback is with the mainline games, will have a domino effect on everything else.
For example, if Sword/Shield got delayed, everything else that is tied and connected to Sword/Shield also gets delayed, the anime, the movies they have planned to release, and most importantly, the new merchandise they have lined up in conjunction with the games. It's far more costly and financially impactful, in the negative way, if Pokemon got delayed than it would be for any of Nintendo's other major franchises like Mario, Zelda, or Animal Crossing to get delayed, which is why Nintendo has been and is far more willing to push those back because the amount of money they make off those games is much more reliant on their actual quality than with Pokemon.
So, delaying the game is not an option. That leaves Game Freak with no other choice but to rush the game as quickly as they can and not do as great of job as they could if they were able to take their time with the games, because the Pokemon Company doesn't want to deal with the after-effects and negative financial repercussions of delaying the entire machine. But what the Pokemon Company and Game Freak both fail to understand, is that with newer, better hardware, ESPECIALLY now that you're developing for an HD video game system that can hold its own against the PS4 and Xbox One with enough effort, requires much more staff, tools, and resources than it did developing for handheld systems that were constantly equivalent to consoles that were released 2 generations prior, (The DS was essentially a portable PS1/N64, while the 3DS was a portable PS2/GCN). So instead of providing the resources and hiring the staff necessary to do so (and it's not like they can't afford it; Pokemon is the #1 most financially successful multimedia franchise in the world, they most CERTAINLY can), they want to cut corners and save money by banking on the fact that fans will just buy the games, no questions asked, and the train will just keep on rolling like it always has been. I'm genuinely concerned that at the current rate and pace they're going, the developers at Game Freak will burn out and get sick of Pokemon, if they haven't already, and start going an autopilot with each new game they release on newer hardware, and before long we're going to get a set of mainline Pokemon games that will be, for lack of a better term, the "Sonic '06" of Pokemon, as I will call it. And if or when that happens, then they'll be in trouble.