I would argue that there should be some sort of regulation that ensures that phones are interoperable with one another for "phone stuff". That is, if you sell a phone in this country, by law it should be able to make a phone call to every other phone sold in the country. The problem is, what qualifies as "phone stuff" is rapidly expanding.
iMessage is a good example. Apple is trying to leverage its dominant market position to make text messaging something that's iPhone only. Remember the whole debacle with people who had an iPhone and then didn't suddenly not being able to receive text messages from other people who still had iPhones. Apple's solution was broken and only partially effective - and I think at least somewhat intentionally so. Same with FaceTime. You want to talk to your friends with an iPhone? Well, you need an iPhone too!
So yeah, we as a society need to decide what we define as "phone stuff". Having the ability to communicate with every other phone for "phone stuff" is critical from an economic perspective, and eventually will also be so from a safety perspective. Requiring inter-phone communications to be standardized isn't too far-fetched of an idea.
(Requiring the same non-phone-stuff apps to work on different platforms though is stupid.)