Why not though? Donaire is the only fighter that give Inoue one hell of a fight, maybe you forgot that the last time they meet, Donaire broke Inoue's orbital bone. So he was close to defeating Inoue in my opinion. If he could have start early and hit Inoue with powerful left then maybe it could have a different outcome.
The final score during their first fight is : 117-109, 116-111, and 114-113, all for Inoue.
Not sure what the first judge is watching, but the second and third judge score the fight very close.
Casimero vs Donaire is also a good match as well. But if Donaire doesn't want the fight and wanted Inoue first then all we can do is wait for now.
I watched that fight and I can say that Inoue got a taste of pinoy flash, and back then Donaire is not in his fighting shape (personal opinion), having away from the ring for some time and not to experience any fight got some impact to boxers conditions.
He threw punches that hurts Inoue but since the champ is very active and still on his prime, after some of those heavy punches from Donaire and feels that he can ignore it,
He brings he's heavy blow, and the timing was perfect. In the last few rounds, he beats Donaire at no doubt.
Moving back to this topic, It's nice for Casimero to get the Attention of Inoue after winning against Rigo, interesting to bring the noise and even before both camps settled, Inoue though will give a rematch fight for Donaire this coming Nov no final date though.