This is quite a sound strategy of retaliation, and I understand and agree with what you're saying, but I'm that player that thinks "ring outs" are effing gay, and honestly pretty cheap when done on purpose. I don't think I'm the only one that feels this way...there's gotta be some reason why you get 0 points for winning a round with a ring-out. I actually back away and let people get away from the edge of the ring, if and when I pressure them into it. I stop my attack and literally back away from them.
Unless of course it's a particularly "cheap and cheesy" opponent, then all's fair.
Well this is something you'd have to overcome if you were interested in playing more competitively. Positioning and ring control are major elements in the overall strategy of any fighting game, aside from older Tekkens with infinite stages. Even in old 2d games, positioning in relation to the corners was important.
Playing fighting games competitively has a lot to do with controlling your opponent's options, while keeping your own as open as possible. If you manage to make effective use of moves to move your opponent around the stage, you can cut off some of his options by forcing him into dangerous ring out scenarios. No reason to back off, because they're far from defenseless, and being put in these scenarios is no guarantee that you'll ring them out, even if you're trying to.
I'll give you an example from Cervantes, who's my main. His A+G rings out forward, much like Mitsu. A player defending against this will most likely want to break A grabs to avoid being rung out. A possible solution to this on my part would be to use his command grab instead, which is a B break. This reverses our position in the ring, and puts my back to the edge, where I may choose to instant teleport from his Dread Charge stance, and change positions again, putting his back to the ring edge, and in another mixup.
None of that is set in stone, as the opponent always has options to deal with any of those. He could take a risk and break B if he thinks I may choose that throw, or if he's low on life and has to guess. He could wait until I teleport past him and attack me before I can force my offense again. He could side roll away from the ring edge, as well. All of these things are factors that have to be considered in higher levels of play.