Staff/Bruce have stated that commenting out individual lines is unlikely happen due to the overhead every action would incur for this feature (makes sense--the easiest way I could see this implemented is an "is this commented out?" check before running every line). That being said, if you just want to temporarily remove a line: cut it! Same effect, and you can paste it back in where it went. You can also cut and paste multiple actions, though you'll have to remember the cutting order since it doesn't appear to tell you what the action it's about to paste is.
Yeah, keep on asking. I asked 12 months ago to reduce the logging for individual devices/attributes, and was told soundly "no". Only for it to happen last week with magical results. Keep asking.
Sounds like you meant event generation history, not logging, the default for which was recently changed (but still configurable). Changes of mind do occasionally happen, but I figure it's worth stating a recently-new workaround since I personally think it's unlikely to happen with this any time soon.
I should have said "event history," not "event generation"--the "logs" of that is what is more aggressively cleared by default now. That is what both that post and I are talking about, not to be confused with the live "Logs" or "Past Logs."