My cat is currently indoor and we take him out with a harness sometimes so he can get some sun because we live in a dangerous area with lots of cars and coyotes. However, I feel bad about not letting him come and go as he pleases because I know he wants to and he tries to sneak past us out of our apartment into the hallway sometimes. If I were living somewhere further from traffic with a fenced in yard I'd probably have a cat door.
It's complicated, whether you choose to keep your cats indoor or outdoor there's going to be someone who thinks you're a cruel monster because of it. Either you're holding them prisoner or putting them in danger, isn't there some sort of sane middleground?