In short, making streaming architectures work require great central planing, a grand architect in the sky, or they fail miserably. I think that is an argument against streaming architectures ;)
The implementation overhead as far as code-to-write for streaming architectures is comparable to CRUD. But there is less knowledge dispersed about practices on how to do it, so there is the cost of learning. It is more cutting edge after all.
Regardless I feel streaming has been around long enough now it should be urgently considered anywhere where the words "data pipeline" and "scale" are thrown around together frequently.