Let me explain, BO2 was released on 360 and PS3, while Ghosts was also released on both but also with the One and PS4 a year later.
If Ghosts was released a year earlier and BO2 was released afterwards while being the exact same game that was released, I don't think anyone would have a problem with that and make the game more accessible by being on modern consoles.
Let's be honest here, considering how greedy modern Activision is, we're most likely not getting a BO2 remaster or even a modern port of the game anytime soon. Which really sucks considering that they could've dropped BO2 on modern consoles at the perfect time with BO7's release, but they didn't so we won't be seeing any old COD remasters anytime soon unfortunately.