It does not send SMS automatically. Just open SMS client
Yes, I know. If they implement it properly it's alright.
But my concern is that a it might get a security vulnerability when a nifty hacker finds a way to automatically submit the SMS.
And in my opinion omitting the feature is the best way to avoid that problem.
To me it looks like another potential security vulnerability that could be abused by malicious websites.
Therefore I'm quite happy that this "feature" is missing ;)