I'm saying it does not matter what someone calls it but those who are insulted when it's called emotional problems instead of mental illness (not those, like you who think it is emotional problems, just those who are insulted if it is called emotional problems) are probably wanting something more definitive.

I believe a problem is always subjective; your "problem" might not be my problem but "illness" everyone pretty much understands. So, if you want to call it an "emotional illness" that might make some of the "mentally ill"-only people happy but "emotional" can be subjective too and does not cover those illnesses that have more than emotional aspects to them. I believe "mental" does because our thinking/brain can cause problems with our body and emotions; someone suffering from a somatoform disorder displays physical difficulties, not emotional ones.