Sure there's an argument that you need to get JR up higher to combate the high OD levels but 1: JR is extremely expensive in the salary calculator 2: Based on the terrible % it produces right now, it simply doesn't look like it's worth it's high price. 3: For some odd reason, players with 9-10 JR don't seem to shoot 3's that much worse than players with 16+ JR. That right there discourages many owners from training it.
The real problem is not so much that it's expensive on its own (it's barely more expensive than OD on a SG), but that the SG formula has JS, JR and OD all highly weighted. If you start with every skill at 10, and then raise two skills to 20, the combination that leads to the highest salary is JR + OD. So of course, if you're going to train JR, and nobody's going to skimp on OD, and you've got to have JS with JR, it's going to be brutally expensive, while skimping on JR and staying in the PG formula reduces the cost of OD quite a bit as well, letting it get jacked up to those levels.
Which, incidentally, is why I still think it's not the engine's problem necessarily that outside offenses as presently constructed are relatively ineffective (outside of very few specialty cases like Silverbacks' team, for example). It's just that nobody thinks twice of having a guard with high OD, passing, handling, driving and even JS, and then dumping IS on them is free, and yet replacing that IS with a decent level of JR gets them onto the SG formula and their salary is busted.