Yes, mileage earning rates on JAL are quite low unless you pay top dollar. Last summer I flew in premium economy on fares that were ridiculously expensive and still only got 70% mileage credit.

As for whether it's worth it to try for 80,000 FOPs, I would say it's only worth it if you can get fairly close to that through regular flying and you would only need to make small adjustments to your travel patterns or pay a bit more on JL to get across the 80,000 threshold. I don't think the incremental benefit of OWE over OWS is worth spending a lot of additional time and money for. (I've had OWE in the distant past but have been OWS for several years now.)