emerge should merge trivial changes automatically. At the moment, the user has to invoke etc-update manually just to see "merging trivial changes in ... automatically". Reproducible: Always Steps to Reproduce: 1. 2. 3.
I disagree. Merging config files at the moment is left to an external program to sort out; it should stay that way. At the moment there is one place for policy on what changes get automerged, if any, and that's in the config file for your config update program configuration (/etc/etc-update.conf, /etc/dispatch-conf.conf, etc). If you add this into emerge, then this becomes two places holding the same policy and two programs trying to do different parts of the same job, which will get messy.
A switch could be added to etc-update telling to "don't do anything than automerging trivial changes" and emerge could invoke etc-update with that switch.
No. You do what you want with protected files. If they were merged instantly, they wouldn't be protected. Besides it's easier that way.