SMS is pretty useless for exfiltrating data, however it's very useful for charging random individuals if you have remotely infiltrated their device IMO
In some countries, special SMS messages can charge you money (billed to either your contract, or withdrawn from your call money immediately if you don't have a contract)... They are usually used for gambling and TV competitions though
Smartphone software most software these days only attempts to prevent unauthorized access to your information. It's up to the manufacturer to determine who is and isn't authorized. Calling that behavior malicious or not is moot point because they all do it.