It really depends on what you mean by characters. Does EU4 have characters? Technically yes, but character interaction is basically non-existent.
Does HoI4 have characters? Again, the answer is technically yes. However, I doubt many of those 27% are opposed to project Caesar having generals in some form.
I would expect it to be combination of people not wanting character interactions having anywhere near the impact the dev diary indicates we might get, and some opposition to character portraits in general. EU4 did fine without them (outside of advisors where they are rather pointless), and ideally I would see project Caesar designed in a way where they weren't needed. As soon as character interactions are an important part of the gameplay (which the are from the sound of it), some kind of portraits to make it easier to distinguish one character whos name people will have problems pronouncing from another.
As someone who hit respectfully disagree to the dev diary for reasons unrelated to 3D models, I didn't even think of that as a possible interpretation of the question. I have however only seen the screenshot you posted here.