They could but it would require a far amount of work and also do not forget that to using android wear OS they do have some of their hands tied on what they can add. They could make an App to handle it but just take.
Google could add some stuff to android wear for the API but at the same time why trust Apple not to break their API with an OS update. Apple OS updates are known to break API and make life hard on developers to address this stuff.
Good points. It is unfortunate, because I would much prefer the look and style of the Moto 360 over the gawd awful looking Apple Watch.