I think partly the difference is in use case. The main app that I work on, for example, probably has fewer than 30% controllers per route, so generating controllers every time would not be a sensible default in our case. And deleting controllers in the moment isn’t super hard but I think when maintaining an app long term, especially a large one, the less cruft you build up the better. Generating unnecessary files would most certainly result in unnecessary file buildup in some apps I know there have been times where I generated things and then never ended up using them so they just sat there.
That said if you really hate creating these things separately you could probably write a couple little scripts and/or custom generators that would create route/controller or template/component pairs for you with a single command.