Yes, it's always been true - though for several years in the early-2000s, ToR's tables had the values reversed because they made the same error in assumption that "bigger is always worth more". They were informed of the error by one of the devs around 2005 and changed their charts. Some places that had copied ToR without permission, instead of using the old EA support file info, had errant information for the next decade because they never bothered to look for updates.
The reason that they are worth more is that the smalls are for the most difficult smith-made weapons in the BOD system.
It's also one of the reasons why then non-6-parters were desirable with some, before the point system.
2-parter LBODs, when exceptional, had a 20% or 90% chance (20 count) of POF. With the point system, now only the 20-counts can be used for POF, but those are an easy bribe (at most, 3 bribes per BOD), and use iron.
Originally, the Normal 20-count 5-part LBODs had a 20% POF chance as well - and could be filled by BUYING all the components to fill, making it a REALLY cheap way to try for POF (though you had to go to a weaponsmith (like the ones in Moonglow and Jhelom), not a blacksmith, to buy the war forks). How cheap? 2k or so of NPC weapons for a 20% POF chance (or around 800 or so ingots if you had to craft, since you could use exceptionals to fill normal larges).
The point changes eliminated the 20ct 5-part Normal's chance for POF, but now you can use any of the 5-part (and 6-part) exceptionals for POF.