Many people object to it on moral or religious grounds.

ECONOMIST: The case for regulated mercy-killing

Then, I think the other thing that comes along with that is that if a parent does come across a game that they feel has gone too far, that they feel has content that they object to, that that makes it something of a moral objection.

FORBES: Ferguson on Better Research, Addressing Causes of Aggression and Mental Illness and Being Involved with Children's Video Game Content

Many of those who object to the change in the law don't point to moral concerns.

BBC: Soft launch for the soft opt out