In the case of Rayman Origins, look at the release dates. I really wouldn't call this a fair comparison with the 3DS version releasing 3 months later than the Vita version and 6 months later than the console versions.
With FIFA, those games are largely European and Europe still seems to be largely Sony territory (look at North American sales of those games) so with games that sell best in Europe, Vita may be a decent choice.
Additionally, smaller (largely Japanese) games such as Fantasy Life (0.36M) and Yokai Watch (0.30M) can also do well on 3DS. Its not a guarantee but its not like these games get buried under all the big name titles like some people in this thread imply.
PS: I have said multiple times that attach ratio doesn't matter and I will say it many more. Would you rather sell 10 games on a console owned by 20 people or 20 games on a console owned by 100 people? I thinks its pretty clear which one you will make more money off of....
Also, saying attach rate should be proportional isn't really fair either. With a cheaper console (and more popular) comes a lower barrier of entry and more people in the "non gamer" category buy the console. So if you look at the amount of people who are on forums like this and who buy games regularly and consider themselves "gamers" you will find a higher % of overall HW sales on the Vita (say, 1 in 5 Vita users are "gamers" while 1 in 10 3DS users are "gamers"), not because there are more "gamers" on the Vita, but because there are more "non gamers" on the 3DS...