I don't think Apple search would provide any tangible benefit for Apple users, nor do I hear any regular iPhone users express any desire to have Apple search, they just use the default. It might benefit Apple though, but why spend money on developing search when you can just use Google and get 36% of the revenue.
The whole wanting a 100% Apple ecosystem isn't something I think many a clamoring, except perhaps the few insane hardcore Apple fans. Also currently the alternative is pretty much locking yourself into a Google ecosystem and that's worse.
