FliteStar 9.04 and FS Scenery question?

I was looking at a real world flight planning programme by Jepperson.The amount of data available is phenominal.There are rivers, coastlines, railways contours etc and it made me wonder whether the methods used for scenery in FS are the best.I know little about scenery construction but why cant all the jeppeson data be used including contour lines for mountains?Peter