Hey NJJoe - you're right in that this is a "voluntary recall." But the "voluntary" part applies to Nissan doing this without NHTSA issuing an enforceable order from them to do it (i.e., the voluntary part doesn't apply to vehicle owners!). Actually, almost 100% of all recalls are "voluntary." Generally, manufacturers will fight this only for so long if they don't want to do a recall. NHTSA then has to go through formal judicial proceedings to get an enforceable order issued. Usually, when manufacturers see the handwriting on the wall, they'll cave and do the recall.
Because the recall is formal (with NHTSA assigned number, etc.), Nissan will want as high a compliance rate as possible. Especially since they have to report the results of the recall to NHTSA, who has the authority to require another recall if the return rate on the first is not high enough. If I (or anyone else) doesn't get the fix done, any subsequent problem (i.e., fuel tank puncture and attendant damage) is on my own dime.
Although I'm not crazy about adding MORE weight to my Murano and potentially reducing wind drag even more (i.e., lower fuel economy), guess I probably don't have much choice on getting this done. Oh well . . .