On the flip side, there are less serious gamers like myself (*) who might consider the buying the 3DS, but would be put off by the fact that to access certain hidden features- or, more seriously, advantages- in games *that you'd already paid for*, you then had to shell out more for these figures which you have no interest in, nor space in your house for.
If some people like that- good for them. But personally, if I'm expected to buy into this sort of thing to get full use out of a 3DS, I'm not even going to bother.
Probably Nintendo have done their sums and research and estimated that they'll make more from tying their consoles to the Amiibo than they'll lose. Maybe they got those sums right, and maybe they didn't- but even if they did, it's possibly not the 100% win that you think it is.
(*) Or rather, people who are *only* interested in the games- casually or otherwise. There are probably many "serious" gamers who have no interest in collecting "Sailor Moon" Happy Meal toys with embedded RFIDs either.