Are you sure it's really "small in capacity"? I was curious so I opened one of the cartridges my printer reported as empty. There was still plenty of ink in it...
I got it. I should put ONLY there. It doesn't matter how much the capacity was, the fact was when I opened it after the printer reported cartridge exhausted, the foams inside were still soaked with ink.
Oh, yeah, I'm sure the manufacturer excuse is that they need a bit extra to ensure print quality; whether or not that's true, ink cartridges of this kind are just a racket.
I'm soooo glad consumer 3d printing has avoided it this far and hopefully the momentum keeps up even as the technology advances.