People choose how they dress/present themselves based on how they WANT to be perceived... I am merely obliging. You don't find many gang-bangers dressed like a Sunday school teacher, do you? Of course not - they wouldn't be accepted by the group they are trying to affiliate with. Likewise, you can gain a lot of other clues about a person by how they look... you can tell which women are likely to be high maintenance types, and which ones are more down-to-earth, which people really don't care at all about their appearance, who is likely to be mentally ill, who is aggressive and who is passive (body language), who is practical and who tends more towards the frivolous, and who considers themselves "cool and edgy".
To pretend that looks are completely irrelevant is ridiculous, but feel free to insist otherwise.
Old people with dementia should be expected to react violently, BTW. If their brain development level is that of a small child, one should expect physical tantrums, just like a child.