Sometimes RCS is available. Sometimes it's not. This seems to be a carrier issue. It could also be related to the fact that if someone using an Android phone uses a non-RCS-compliant texting app, the message will go as an SMS. And yes, someone with an Android phone could have more than one messaging app on their phone.
Only you can say if it matters to you. I rarely send pictures and never send videos so SMS has never been an issue for me. I don't care about the little typing indicator dots as I don't have the time or the patience to stare at my phone, waiting to see if someone is answering me right this minute. You may have different priorities. Since I don't care, I never pay attention to which protocol the phone is using.