Why hasn't there been any EMD SW series (ie: SW7) add-on for MSTS with custom cabviews and sounds?

Why hasn’t there been any EMD SW series (ie: SW7) add-on for MSTS with custom cabviews and sounds? I really would like one, and I am curios about what an SW cab looks like.

Look at www.train-sim.com. There are a few in the Dl’s

http://www.strategyfirst.com/en/downloads/demos TrainzUTC.