It doesn't seem true to me that the "V" React gives you is so good that you don't need anything else. It does seem common (though not universal) to eschew MVC for React apps, but in most cases it is replaced with something like the Flux architecture, which is no more or less complexity than MVC, it's just different.
Even inside Facebook Flux isn't used everywhere; Yes, for heavier modelling, sure. But for most common cases you're very fine with using only js objects.
