Sure, android might be good enough for most people. But that's like saying porridge is good enough for most people. I want a steak, or a burger. The problem is that I don't really have a choice right now, I don't want porridge.

Additionally, even if you trust Google today, they can turn evil tomorrow and then we'd have >75% of people who are using android without any options. Diversifying the available options in the market market is good for everyone except Google.