> Over my lifetime they seem to have both shrunk and become much more reliable so someone is iterating and improving the designs, just not at a high speed we ar

> Over my lifetime they seem to have both shrunk and become much more reliable so someone is iterating and improving the designs, just not at a high speed we are accustomed to in the IT world. The reliability is one thing, that got improved mostly by better monitoring (you can spot early signs of degradation by analyzing the oil for residues indicating arc discharge), but the size is in the end fundamentally dominated by physics - you need a minimum gauge of copper wire to transfer a given current. The only way to improve the size of transformers will be the widespread availability of room-temperature superconducting material, which is as of now not even theoretically predicted, much less proven in practice.