One thing the sales charts continuously prove is that lack of originality is the LAST thing to stop games selling.
yearly Call of Duty, Assassin's Creed.
every Pokemon exactly the same structure
People sub to WoW for 10 years
Well, Zelda is accused of being a stale rehash nomatter how much it changes, so the critics will say the same as you're saying about those other series. But even though A Link Between Worlds is panned for looking just like Link to the Past, reviewers treasure it for changing things up a little. Such positive buzz WILL generate sales.