Exactly. It is not really possible to predict what Sakurai is doing. You'd have an easier time programming a random generator that selects one out of 1,000 characters and predicting which character would be chosen for the next smash.
I'm not sure why everyone is acting like Sakurai did something shocking and unprecedented? Wii Fit Trainer, yes, none of us saw that coming, but none of us expected Game and Watch or R.O.B either. More then likely she is our token surprise character for the game, we just had the benefit of not having to wait until the games release to find out. Not to say we won't have anymore surprises but you all know what I mean. Even with all that being said she still makes a lot of sense. Wii Fit was one of Nintendo's biggest games, ever. The series became a cultural fad that sparked much of the fitness game movement that followed after it. She's surprising and makes people want to play her, that's really all that matters.
Villager was one of the most requested characters back during the time of Brawl. Animal Crossing itself has become one of Nintendo's largest series to the point where I'd say only Mario, Wii ___ and Pokémon edge it out. The only reason he wasn't topping our charts is because of that Iwata Asks interview long ago, but given how he has changed his mind in past times it really is not that surprising in hindsight.
And Megaman... Well, do I really need to say much? One of the top requested characters for Super Smash Bros for awhile, was probably the top requested character overall before the reveal, and a beloved gaming icon. The only real surprise is how Nintendo managed to do a better job with Megaman in one crossover than Capcom has done in several years.
Even if you set aside the legitimacy of the recent rumor pertaining to Little Mac, Mii and Pac-Man; they still make a whole lot of sense as playable characters, regardless of our personal feelings. This idea that Sakurai is just willy-nilly throwing stuff against the wall that make absolutely no sense is a little bit disingenuous to him.