Okay, I understand your point now. And yes, if anyone wants to replace the current SMS/MMS technology, it's important to have an app on the phone that doesn't require creating another account. But, here once again, it's Apple who is preventing that from happening by refusing to allow any such apps (because they would compete with iMessage) to be available to users in the App Store. If Apple made Google's messaging app available on the Apple Store, or if they made their own iMessage available in Google's Play Store, then people would have the choice. But Apple famously doesn't want to do either of those things.