This is one of the selling points of iOS. Your messages are protected from random app developer boobs.
Years growing up with Windows taught me that unfettered access to any and all devs is a recipe for disaster. I whole heartedly embrace a few minor feature limitations. Have yet to have to go clear viruses and malware off family or friends iPhones and iPads, its freaking great.
Apple reviews every app that goes into the app store. I'm sure they'd notice if it was sending all of your messages to a hacker. There's not really any excuse not to allow this sort of thing.