Solution or Workaround
Why are some AutoCAD entities simplified to single thickness lines when
displayed in ArcView?
Certain symbols in CAD drawings, such as some arrow symbols are created by starting with a light weight polyline and specifying a different thickness for the beginning and end of the line. This results in a tapered line. These symbols are stored as blocks. ArcView cannot display blocks directly, so it must explode them to get to the underlying entities. When blocks are exploded, any lines within them will lose their thickness values. So arrows created by assigning different thickness at the start and end will come into ArcView as simple lines.
If your symbols were created in this fashion, you must create a new symbol which does not use varying line thicknesses to control its appearance. In other words, a tapered line can be created as a polygon using lightweight
polylines to form the border of the line. The lines forming the new arrow
symbol can be saved as a block. When ArcView imports a drawing containing
these symbols and explodes the blocks, the symbols will still look the same in