No, you're misunderstanding what I meant. In short, when Igor's Japanese VA died, Atlus showed a reluctance to replace him, and they reused previous lines of his in new projects. This is part of why everyone freaked out when they saw him in trailer PV01, because it was still up in the air if Igor was really going to be returning for P5 after all this.
So when his new voice was heard, the vast majority of the fans who knew about this situation then presumed that it was Atlus finally moving on with the character, and intentionally giving him a distinctive new voice instead of trying to mimic the old one. No one thought anything past that.
So when the fact that there WAS a reason for the change in voice happened, that took everyone by surprise, because it's not something they had been actively thinking about. This was set up from the very first voice you hear when starting the game.
1. There are twin Velvet Room attendants for a single host instead of one.
2. Igor doesn't fuse himself, the attendants do it.
3. Fusing is done in a very vicious way that is not the same as how the previous games were.
4. The Velvet Room host does not sign a contract or receive a key when entering this Velvet Room, a crucial element.
5. Neither of the attendants have a grimoire.
6. Instead of being a welcoming environment where the host's path appears open, this one is an oppressive one where his fate seems sealed.
7. Fake Igor saying "Welcome to MY Velvet Room" instead of "Welcome to the Velvet Room."
Etc.
All of these reasons are why this twist cannot just be said to be tacked on. It fits into the core of Persona 5's theme, as well as the motivations of the final boss. The spirit of rebellion extends towards the one thing in the series you wouldn't think you'd be rebelling against. This is why I say that those who have played previous titles in the Persona series, and have inevitably spent tons of time inside the Velvet Room and with Igor, would be particularly affected by this twist instead of those who have only played Persona 5.