Who wants one platform? I am all for having multiple platforms. I would argue that no one platform is ever going to be best at EVERYTHING. Without getting too in depth we can look at security for a quick example of how platform diversity is actually better for ALL consumers.
RIM v iPhone
RIM is leaps and bounds ahead of iOS in regards to device and information security however I would argue that iOS is equally ahead of RIM when it comes to overall ease of use and device features.
Apple is catching up in that regard. My better half works for Hilton Hotels, and they sent out a memo several months ago that anyone with a corporate BB could switch to an iPhone if they so desired. Or have their personal iPhone bill subsidized if they wanted to go that route. So I don't think iOS is all that far behind RIM in security.