Embedded is good for POC deployments and scenarios with limited resources. Very surprised VMware recommends Embedded now, here is why:
The big negative with Embedded vRO is that it shares the same VM/Postgres DB with vRA. With Embedded, any vRO maintainence (Plugin Installs, Sync Issues, Updates, Certificate Replacements, etc.) that requires a reboot will require you to reboot vRA with it, because it's the same appliance. vRA with Embedded vRO takes ~10 minutes to boot up and start all services, whereas External vRO is ~90 seconds. And you cannot migrate Embedded vRO/vRA Postgres to External vRO Postgres. Plus, with Embedded, you cannot use a vCenter/SSO Authentication source.