Bard jewelry is shared with ninja because they're both DEX classes. Honestly the jewelry situation is just fine since it's based on primary stats and nothing else
Bard left-side equipment is NOT shared with ninja because...well, just LOOK at bard gear and try to picture a melee class wearing it. So they tacked DEX onto the monk gear and now those two share it.
...personally i would've liked if they had opened up that gear to BRDs as well since not all of us want to look like we just got back from carnivale, but I digress.