I am answering my own question once again,
Ok after some trial and error testing, no it does not. It is simply a measurement unit.
Let me give you an example:
Let's consider that we have a circle with a circumference of 100mm. We can have 1000 plotter units of 0.1 each or 100 units of 1.0 each. Its the same thing and it does not affect in any way the quality of the export.
PLT files are polygons or polylines if you prefer this. The nodes are still in the same position if we have 1000 PU or 5000 PU and they are of the same quantity.
However there is one parameter on exporting PLT's(HPGL) from Corel Draw which called the Curve Resolution. That parameter indeed affects the number of nodes(number of lines) that the exported PLT will have on every curve. If the Curve Resolution is high this means much more nodes on each curve hence better quality on export.