RCS is all the rage right now, at least for Google Messenger users, in the U.S for Verizon users. And you could kind of say the same for Reliance Jio users in India, except I'm yet to come across people who actually use the Jio4GVoice app to send SMS, because why use it when WhatsApp is there?
Anyway, this is the biggest complaint for me too. Jio is restricting RCS to its own app, and it is not fully RCS yet because of the mandatory rule to use its 4G LTE network (even on VoLTE devices) for the app to work. Why can't I use Messenger and Wi-Fi for the same? Well, Textra SMS may have given the answer to this question.
In response to a user's query on Twitter, asking if Textra SMS would get RCS support, the SMS app developer responded positively. But they also said that it will take time, and that carriers may only implement RCS support in mid 2017.
The SMS replacement rich text messaging service, is the future, there is no question about that. But we have to remember that RCS is still in sort of a beta phase, which is why only one network in the US has it for now. The same can be said about Jio. The restriction for the Jio4GVoice app to use its own network for RCS, is because, other telcos like Airtel, Vodafone don't have RCS yet, so the lack of the new network protocol, means that the messages probably won't be delivered at all. And the SMS/Call options in the app, probably uses some sort of conversion (VoLTE to GSM) for regular SMS messages/voice calls to other networks.