As someone currently running a bitnami wordpress site on aws it's pretty nice being able to SSH in and change whatever you want. Bitnami gives you a reasonable starting point but then you have a lot of flexibility over how you manage the server. Maybe installing everything yourself isn't too hard, but I only run the website because I happen to be the most technically competent person around so it's nice not to have to think about it.

Admittedly I've only tried one managed wordpress service, but it was total garbage in comparison. Debugging basically involved opening a support request because even the most basic tools weren't available.