iMessage is more conversational because it's what most people are used to using and seeing. People generally associate green bubble messages with spam/transactional messaging and blue bubble with trust. Additionally, iMessage also has additional features such as typing indicators and reactions (likes and loves) that makes the interface feel more conversational. WhatsApp could also be very conversational, but most people in the US use iMessage.
As someone who has no legal duty to advocate in your best interest, I think you should keep posting about your intent to damage the platform-holder whose terms of service you are contravening.
RCS has most of the features of iMessage, including tapbacks and large attachments. It's even cross platform. iMessage is the channel where Apple users communicate with their friends and family. Exploiting the trust users have in iMessage by injecting unsupported business messages into it degrades the value of the channel by destroying the very trust you are relying on. This model is about as sustainable as burning coal to generate electricity.
Reading your responses it seems like your angle is to fake looking like a human by using the blue bubble. Are you worried your users will ruin the trust of the blue bubble thus killing your product with your product?
