@VSarius I've often said that I prefer unrestrictions rather than restrictions to shake things up. But of late I am unsure if this will ever happen. Cards that are more than "safe" would need to be unrestricted to shake things up, in my opinion, and I'm not sure how much people want that.
The last few cards that were unrestricted didn't have a major impact as far as I know, but I could be mistaken. Regrowth, Gifts Ungiven and Thirst were all released and failed to make a major impact, in my opinion. All these cards were ones that people here said would "destroy vintage and take over the format".