Two answers. Pressure and they're not big enough.
Now, you see, in order for hydrogen to be metallic, the interiors of Uranus and Neptune would have to have more pressure.
Pressure can be defined as the exertion of force upon a surface by an object, fluid, etc., in contact with it.
The three states of matter on Earth are solid, liquid, and gas. An element's shape is determined by its temperature and pressure. On Earth, hydrogen is generally a gas, but it may be intentionally cooled and compressed to change its state into a liquid or a solid. Hydrogen is still a non-metal even in these states; since its atoms strongly cling on to their electrons, it has poor electrical and thermal conductivity. Contrarily, metals have good electrical and thermal conductivity due to the arrangement of their atoms, which forms a lattice that makes it simple for the outermost electrons of one atom to go to another.
Jupiter and Saturn are the two gas giants in our solar system. Based on their densities, both planets have a considerable amount of hydrogen in them. However, the hydrogen in these giants is heated and compressed to such high temperatures and pressures that it assumes a number of peculiar phases, including liquid metallic hydrogen. Hydrogen, as I previously stated, is a non-metal. However, in Jupiter and Saturn, the extreme temperatures and pressures cause hydrogen atoms to lose their electrons, resulting in a stew of free-floating hydrogen nuclei (protons) and electrons. The ability of the electrons to travel freely between the nuclei due to their unbound state is a characteristic of metals. This is metallic hydrogen, which has a metallic-like behavior. Metallic hydrogen is conductive and is thought to play a significant role in the dynamo that drives the magnetic fields of Jupiter and Saturn. (However, the dynamo on Earth is propelled by liquid iron, a real metal.)
The ice giants of our solar system, Uranus and Neptune, are too dense for hydrogen to make up a significant portion of their composition. In addition, because of how similar their masses are, planetary scientists presume that the innards of these two planets are comparable and that hydrogen makes up just around 15% of their masses. Although hydrogen is thought to form a liquid molecular shell deeper into Uranus and Neptune and is present in their atmospheres, it never experiences the pressures and temperatures necessary to transform into metallic hydrogen.
Thanks.