The gimmicks implemented into Pokémon Sword and Shield's battle system this time around are known as Gigantamaxing and Dynamaxing, and the former makes the latter pointless. Dynamaxing was the first mechanic revealed for the games, and it essentially turns any Pokémon into a massive version of its original self. The mechanic received a mixed reception when it was shown because it doesn't play with the main appeal of the games, which is form-changing through mechanics like evolution or even the temporary Mega Evolutions.
Not content on just delivering massive Pokémon, developer Game Freak pulled the curtain back on a new mechanic known as Gigantamaxing. Much like Dynamaxing, Pokémon that make use of this ability balloon to massive proportions, but these creatures also change their form. This makes the technique infinitely more appealing to fans, as the act of supersizing a monster is at least somewhat justifiable.
So, what's the point of Dynamaxing when Gigantamaxing is so much more engaging? There's not much outside of battle tactics. The act of having Dynamaxing allows every Pokémon to take on an opponent who has done the same. Still, past games have featured battle-changing mechanics like Mega Evolutions and Z-Attacks, and those were limited to a select number of Pokémon. Game Freak managed to find a way to balance those encounters, so there's no question that the same thing could have been done here.
So if it's done just to become a constant in battles is there any real point to it? Gigantamaxing at least frames the kaiju gimmick with an evolution, which is ultimately a large portion of the appeal in the Pokémon games. When stacked up to each other, there's really only justification for one and not the other. In many ways, Gigantamaxing makes Dynamaxing completely lackluster in comparison.
This will likely benefit the raid system that is being added to Pokémon Sword and Shield, in which players will team up to take on a giant beast. These encounters mimic what is seen in Raid Battles in Pokémon GO, where the creature is also ballooned to substantial proportions. Pokémon Sun and Moon's Totem Pokémon also played a similar role though, and they didn't require that all other pocket monsters could balloon out to kaiju proportions.
Perhaps the ability to Dynamax will grow on players as more details on the games are shared. Admittedly, seeing an even larger Galarian Weezing in Pokémon Sword and Shield would act as a reprieve of sorts. Until there's further justification for the system though, Dynamaxing just doesn't hold water when compared to Gigantamaxing.