I agree that this should be an option, but not on CarPlay or while driving....it's for safety reasons (and is actually the easiest way to do this).I'll be honest I didn't know you could do that, and I only use AppleMaps.
Thanks for the tip, but Apple has to makes this feature more available and not just through Siri. I NEVER use Siri with AppleMaps. There needs to be an "Add Route Stop" button or something like it.
Adding a pre-planned waypoint only makes sense as a feature when Apple Maps is opened as a web based solution like Google Maps, not just an "app". Not that they couldn't add this feature...I just think that a web based version of Maps would help with this as well as general map editing and suggestions. Nerds like me would sit on my non-Apple PC and make edits all day long if that was an option. I'd even say they should make it iCloud based as a requirement so they can track user submissions like they now do with iOS 15 Maps.