An avatar is a mortal shell constructed to hold a godlike entity from a higher realm. Gods cannot pass into the human realm due to a mystical barrier that separates both realms. These avatars function as a bypass for a deity to allow them to walk among mortals, built by the followers of that deity. They are "landing zones" that provide a deity a place to be summoned into and inhabit and are built to specific instructions to be able to contain it. These avatars are 25 ft tall and must contain multiple compartments to house the soul of a god, which is massive. To fit into this body, a god must divide his soul into pieces to fit in their separate compartments, which are similar to cells built into the avatar's body. Once sealed into this mortal form, it can activate it as a shell to house its spirit. Unfortunately, its large frame is inconvienent and somewhat cumbersome, and its goal is to find a way to squeeze into a smaller body which is more sufficient to use among humans. This so far has been unatainable.
As technology becomes more advanced, it has the ability to get smaller and more operable. The computers of WW2 were like a billion feet fall, taking up entire rooms to do the most basic things. Today, they are as small as a MacBook pro or even an apple watch, which are hundreds of times more powerful and efficient. As power and ability increases, the size of an object shrinks. This is even evident in the human body itself. A single strand of DNA can store up to 700 terabytes as it is incredibly dense as a storage medium. This is as large as a single droplet in your hand. The best solution would be to make smaller avatars with more numerous compartments. A smaller body could contain double the compartments of a larger avatar, increasing as needed. As the entity can divide its souls enough to allow it to fit into any frame, this should not a problem.
What would force an avatar to maintain the current standard size of its frame?