I totally agree with you, and i think the main reasons for people reacting badly to those that are different to them are:
a) Ignorance...they don't understand why they look/act differently to themselves so they are unaccepting
b) Fear. Although society has moved on a lot, there is still a certain stereotyped fear amongst some cultures/families/generations that mentally or physically different people are somehow dangerous. I don't know why this is, but i think it also stems from ignorance and a deeply wrong perception of what disabilities actually are.
c) Trying too hard! People realise what the 'problem' is, but try too hard to act like its cool and nothings different by overcompensating. This can be just as bad as ignorance. Just because someone has a disability of some sort doesn't make them a charity case!
Anyway, i totally agree with you that they can often be the most beautiful people, but unfortunately the world of stereotypes and false beliefs means its taking a bit longer for some without first-hand experience to feel the same.
It angers me too, but on a day-to-day basis the only thing we can do is act how we should - never, ever mock those different to you, treat everyone with respect, and value every single life with equal reverence.
Congratulations on your pregnancy by the way :)