Making good sequels isn't really rehashing. They're changing it up everytime and always adding something new so it stands out. As much as I hate to be the guy who says this, Call of Duty is what rehashing is. Not to mention, it's been years since Pikmin 2.
Also why put Mario on a break? Shigeru said back when he was first made he wanted Mario to be in everything. People want mario, as much as people will deny it, everybody always buys it and enjoys it. Could you imagine if say we had Mario Galaxy 3 (obviously I made that up), Mario Kart, Mario Party, New Super Mario Bros. U and all of his good titles in one year? That would be epic! They're also all different types of games.