I won't question the acceptability of his hobby -- I don't think that's the place of an internet message board. It's your marriage, your husband. If you do not suspect him of ill-will during his guys nights out, neither should any one else.
My husband by no means goes out twice a week, but a few times a year he gets together with his buddies and they have a guys nights. For us, I am friends with all his friends wives/girlfriends -- we all have the same group of friends -- so the girls generally will have a girls' night the same time and then we all meet up later on and have some drinks together to top off the evening. All that said, if I wasn't friends with his friends "women" I still would think his guys nights out were a positive thing. Everyone needs hobbies and couples need time away from one another. I am guessing you don't have children and you're free to do as you please when he is away?
In that case try scoping out local book shops you might like to browse, take a class at a gym, get some girlfriends together for dinner or a movie, or just to hang out on your patio, etc.
Some of my fondest moments with my husband have been those when we're reunited after a short hiatus from each other. It makes you appreciate what you have that much more.