Iodine has an Ar of 127, so I₂ has a molecular mass of 254. Compare that to H₂O, with a molecular mass of 18. That makes the molecule of iodine about 14 times heavier than water.
Hydrogen bonds are why the water has such a high melting point. Hydrogen sulfide is heavier than water but gas at room temperature. But the mass of a molecule has a very large effect on its state.