your missing nothing. I have used grolch bottles for years and they are great. At one point I had a local bar owner saving his empties for me and I amassed quite a few. I gave cases of them away when I started with the kegs. I still have a case or two that I fill off the keg with a counter pressure filler.
The only downside to those bottles is the green color will not protect the beer from light. So store the beer in a dark space. Basement, closet, etc... Not in the sun room.