Scientific publishers, through the Association of American Publishers, in Nature, and in Science, have welcomed the decision.
Many (but certainly not all!) scientific publishers are just leeches on the body of science, profiting from the work of scientists and researchers - most of which they do not pay for.
Elsevier is the the prime example of such parasite, operating with a nearly 40% profit margin and an annual revenue of over $2bn.
There are also ethical and responsible scientific publishers - for example American Physical Society, AAAS and the Royal Society of Chemistry - which try to provide a service to their community, rather than making a quick buck.
As long as elseviers of the world continue to exist and hold a large fraction of our accumulated technical, medical, and scientific knowledge to ransom, so will sci-hubs - which are just the other side of the same coin.
Unfortunately, sci-hub also ends up hurting the responsible publishers. Because they are operating on much thinner margins than the scalpers, they may not be able to survive the damage - so the end result may be opposite of what sci-hub founders (presumably) intended.
In the end, most of our scientific knowledge has been paid for by the public - ie by all of us - so we need to find a way of making it available as widely as possible, while still somehow paying for its dissemination, maintenance, and conservation. Neither Elsevier's not the sci-hub's models appear to be the right answer.