This reinforces the adage (that used to be true) "nothing gets deleted from the internet" and so I am for it. I hope useful posts will be un-404'd.
I.e what unddit.com did for reddit
What're reddit decided to do here is almost certainly against european law and I expect we'll hear more about it over the following months.
I do like legislation that stops big players from using their resources to be exploitive, and I understand the right to be forgotten for individuals.
The other edge of the sword is all the reasons why information wants to be free. I am biased towards this side.
Either way, I think it's important to remember to operate under the axiom that nothing is deleted from the internet. Deletion (by legislation or by privacy tools and services) is a cludge, and saving and resharing is the natural force.