Lockheimer notes that Google isn't asking Apple to make iMessage available on Android. Rather it want the company to support the industry standard for modern messaging (RCS), just like they support the older SMS / MMS standards.
Why is this important? Phone number-based messaging is the fallback that we all know will work. If you want to reach someone and you don’t know whether they use app x y or z, you have high confidence that sending them a text (SMS) will work. That’s because it’s a standard and supported by essentially all mobile devices. That’s probably why Apple supported SMS to begin with.
SMS has evolved, and it’s better. You can see read receipts, typing indicators, better groups, secure 1:1 messages (groups coming soon) etc. That new standard is called RCS, and it’s available now. Supporting RCS would improve the experience for both iOS and Android users alike. That’s right, RCS will also improve the experience and privacy for iOS users.
By not incorporating RCS, Apple is holding back the industry and holding back the user experience for not only Android users but also their own customers.
Apple has yet to comment on supporting the RCS standard. You can download the iClarified app or follow iClarified on Twitter, Facebook, YouTube, and RSS for updates.