Can someone please highlight the allure of having android apps run on Chrome OS?

As someone who has minimal experience with Chrome OS, I struggle wondering why users are so interested in running android apps in Chrome OS. It seems to me the vast majority of apps i use on my phone would serve little utility on a 12-15 inch screen. Can someone very briefly explain to me the advantages one would attain using an android app on a platform geared towards desktop replacement? In my mind all I can think of is the old android laptops, and Chrome OS seems to be so much more than that..