This assumes that, generally, native apps are more buggy. Why? This is contestable at best, or getting it the wrong way around at the worst. Perhaps at the hands of inexperienced developers it's right. But experienced developers coding in native APIs will probably produce an app with fewer bugs.
And we are talking about a billion dollar company. It can afford a handful of really good native developers for each platform. It can attract talented developers who can write cross-platform native code.
Cross-platform toolkits introduce their own class of bugs, which might require patches upstream to resolve, or annoying local forks.
As for the economics of it all, I'll leave that to the other sub-comment which deals with that with an excellent analogy to Apple. People will pay for quality.