Well, we still have 2d around. One of the biggest selling steam games of the moment (Terraria) is 2d. Dozens of 2d-games are still released to the market. The fact that we have 3d shouldn't mean that all other viewpoints should die in a fire, ESPECIALLY when it's just about the personal preference. I don't think making a game that uses a primitive viewpoint is taking a step backwards, if anything it's bringing different possibilities and genres to the market, which is a good thing. I am not denying that Fallout 3 or NV are good games, 'cause they are, I am simply trying to defend another, different style of making a game.
Like Cowabungaa himself said, why limit your options? I personally think that letting a game-style die isn't giving options, I think it limits them. Letting this viewpoint die, would mean the death of another style of game. Even though it may be limiting to use isometric view, that might not be a bad thing. That is like saying that there is no use of using 2d, because 3d let's you see more. I don't really think having isometric games would hurt the industry. We have licensed games to do that.