I don't get why Americans cling so dearly to SMS.
* Apple is really popular in the US
* Apple users tend to rely heavily on Apple's default applications
* Apple's messaging app is the default, and works fine with other Apple devices, but sends shitty SMS or MMS to non-Apple devices
SMS would disappear tomorrow if Apple adopts RCS.
And if they allowed iMessage clients on other platforms, they could corner the entire messaging market.