Please indicate the units you are using as this is variable. Presumably the values refer to millimetres.
These are pretty coarse adjustments.
I would think that 1/100th of a millimetre (~0.028pt) is fairly fine and that “coarse” is a relative term. While I understand to a degree what you are indicating, Draw is not a CAD package but rather a basic drawing component of an office suit. The ODF v1.2 specification does not as far as I can tell explicitly indicate that 1/100th mm is a limit even though it seems to be in LO (and is mentioned in the source code in various contexts). There is however reference in this spec to the SVG v1.1 and XSL v1.0 specifications, in the context of units of measure. Both the SVG and XSL specs define 1px as ~0.28mm / ~0.79pt i.e., 90dpi.
Assuming that LO was designed this way, what is the best way to request that this be fixed?
Well, “fixed” is probably not the right term in this context. There does not appear to be any open enhancement request relating to line / stroke widths. You would need to outline what you would like to see as being the minimum unit (e.g., thousandths of a millimetre), raise a bug and clearly indicate that it is an enhancement. Provide as much detail as possible and then await a response from the QA team to assess the request.
If you do raise a bug, please report a link to the bug back here. The notation “fdo#123456” will automatically be turned into a link.