I often hear people admonish dog owners about playing tug games with dogs. I understand why people suspect that teaching a dog to release toys is important but that doesn't mean play is out of the question unless there's a known problem. Games dogs love are a great training tool that should not be discarded because they remind us of other behaviors.
If your dog often takes your belongings and plays keep away, Tug games are exactly what he's after. Why not play when you say and with approved objects so you don't have to lose a slipper when he decides? If your dog guards items, like his food, from you, you can use games to teach him that your approach is always a good thing. Or teach him to trade his food for better treats and toys until he just doesn't see the point of fending you off. Tug games are sometimes so valuable to a dog, they can be part of reaching a new understanding.
Contrary to what you have heard, tugging can teach a dog to be gentle. If your dog loves the game and you stop playing as soon as a certain threshold of grabbing is reached, your dog learns to stay below that level of excitement to keep the game going. If your dog is shy, teaching tugging on a towel can build his confidence with people, hands and reaching as well as heightened levels of activity.
So don't throw out the baby with the bathwater. Anything your dog wants is a tool you should keep around. But use it wisely to teach your dog what you want....what it takes to get a good game going.