Yes, this is a tragic accident that meets the serious level according to the NTSB. Is the operator liable? Absolutely. But you don't go around re-creating laws that already exist to prevent stupidity.
If the toddler were hit with an errant baseball pitch and lost an eye in the accident, don't you think the person who threw the ball would be liable? There are already sufficient laws against causing harm to anyone, anyhow. What possible good does it do to add more laws just because the instrument happens to be a drone and not a baseball?
Because Steve, we try to manage risk when we recognize it. We don't just shrug our collective shoulders and say "well stuff is gonna happen regardless, so we will deal with it when it does."
We don't outlaw cars because they crash and kill people, but we manage how cars are operated to try and lessen the risk.
We don't outlaw swimming because thousands drown each year, but we try to lessen the risk by teaching safety and having lifeguards at public pools.
We don't make it illegal to keep dogs, despite the fact they maul children or kill about 50 people a year, instead require dog owners to keep them leashed and under control while in public.
We need to ask the same of drone pilots, and that will require laws to try to enforce such compliance, but more realistically, to punish those who don't.
And those laws are going to have to specifically target drones. I see at least one forum member each month make a post about being in a public park/condo/resort where it is clearly posted that "RC planes, cars and boats" are not allowed, but they argued with the police/security about their "right" to fly their drone because it is not an "RC plane." That is the mentality the law has to deal with.
That, and those people who will argue that a drone to the head is akin to being hit with a nerf ball....