we are having a great discussion on the necessity, or not, of having revision/version of the parts in the Bill of Material.
Can a same part number have different revision levels? If the answer is yes, you want to make sure the proper revision level for the component is identified, don't you? If the BOM is used for that purpose, then, the obvious answer is: yes, the BOM should have the rev level of the part.
However, if the parts are issued and verified through other means, the BOM might not need to have the information. I have seen many different systems at work. In aerospace (most companies), for example, when a part gets reengineered/revised/changed, the P/N is changed as well. So, a same P/N does not have different revision levels.