Just because homosexuality was at one point mislabelled as a mental illness doesn't mean that other mental illnesses are mislabelled!
I think bipolar and other mental illnesses should be MORE medicalised, in that they should be treated the same as any other medical condition, such as diabetes, dyslexia, etc.
Not attaching a label to a condition doesn't make the condition go away, it just leaves the person bewildered as to why their brain or body doesn't work the way the majority of people's do, why they function differently. It also prevents them from accessing assistance to help them to either navigate their way through the world, or to simply survive.
You can't prevent a feeling of 'other', all people are 'other' in some aspect of their lives, gender, colour, culture, citizenship, education, etc, etc, etc.
What is needed is to prevent people seeing 'other' as something bad, that being 'other' is somehow worse rather than something equally as valid, just different.