They're not the ideal approach shots for most people, but there is a situation when they can be very effective; when your opponent has a weak backhand. I use an inside out forehand to right handed opponents and very often, I get a weak response. I've found that it's a very good time to play the net and I've picked apart many weak backhands this way. Heavy paced, topspin shots are often more difficult to return from someone's weak, backhand side than a low, sliced ball, which is considered a good approach. A topspin approach shot can be a good approach when used properly.