First, this isn't a Google app. Google is pushing the RCS standard, a standard that some carriers already support.
And yeah, it doesn't support encryption so it's clearly inferior to something like Signal, but open standards that don't live in a silo are still important. For instance, I have friends that almost exclusively chat through Facebook Messenger. Since I won't install Facebook Messenger, I chat with them over SMS. A "better SMS" would be nice, and might help ease people out of the FB Messenger silo.
And yeah, it doesn't support encryption so it's clearly inferior to something like Signal, but open standards that don't live in a silo are still important. For instance, I have friends that almost exclusively chat through Facebook Messenger. Since I won't install Facebook Messenger, I chat with them over SMS. A "better SMS" would be nice, and might help ease people out of the FB Messenger silo.