Well there are certainly many freedoms that we restrict or completely deny just because of the potential to misuse them (e.g. freedom to own a gun).
I don't think this is the case though, and I agree with all of your second paragraph. But I do think (and it seems that) potential to misuse a freedom is sometimes enough to restrict it, even completely.
This is a good point - we can't be scared of everything on the basis it might be misused.
The challenge is to have proper regulation, with the right checks and balances in place - I don't think anyone is suggesting you can just rock up to your local euthanasia corner-shop and say "can I haz dead pls?".
This is a freedom for which many, including myself, may eventually benefit versus the alternative. I may want to make such a choice for myself (hopefully many years into the future!) rather than live in agony and I really hope the option will at least be there for me in my country.