Amy made her own choices in life, after all she was over 18. Her parents couldn't stop her doing what she wanted any more than your parents could stop you. When do parents stop being responsible for their children?
As for the statue, if the owners and audience of the Roundhouse are OK with it, then I don't see there being a problem. She may not have been the role model that society wanted (most famous people aren't) but that's not what she was here for, she made an amazing contribution to music, which was why she was here. It's also nice to see from the link provided, that her foundation is very active and seems to be doing a bit of good.
I hope the poor woman is resting in peace.