You make a great point that when everything is on kube it’s easier to manage.
But… if you are maintaining storage buckets and stuff elsewhere (to avoid accidental deletion etc, a worthy cause) then you are using terraform regardless. So adding RDS etc to the mix is not as tough as you make it sound.
I see both sides of the fence and both have their pros and cons.
If you have great operational experience with kube though I’d go all in on that. AWS bends you over with management fees… it’s far more affordable to run a DB, RMQ, etc on your own versus RDS, AMQ