One quick answer for this is quite simple, if you're in need, you improve yourself and you try to catch a many costumers as possible, if you're on the top and unchallenged, you don't need to improve or change, you’ll not do it since it may as well be a negative change.

This is why competition on the market is good, this is why the console wars is good, this is what naturally happens when you have competence, you compete, you improve, you have to adopt costumer friendly policies in order to keep your sales.

If you ask me, I believe that Sword and Shield is going to be a stain on the history of Pokémon, but in the long run is going to be beneficial for the costumers, they had the monopoly in the "Monster Trainer" genre for too long.

I didnt even know they had your currently known rival start with the weaker type starter. To hell with that shit!