You can also have them supervised outside or on a leash. You're presenting this as a false choice between two options: keep them locked up forever, or let them roam unsupervised.

There are ways to be a responsible cat owner. Letting them decimate local birds, reptiles and small mamals is irresponsible.

Also, allowing pets to wonder and be hit by cars is very irresponsible pet ownership as well. I get so pissed off at whoever the guardian was any time I see a cat or dog hit on the side of the road (happens too often around here). If someone let's their animal wonder freely and it's struck/lost/killed, the pet's guardian is fully responsible.

"My cat/dog knows better.." Yeah, until they don't and they're dead....