I haven't really been able to find a question that asks exactly this. Though Should we edit old, non-interesting questions? is a close match.
Recently I've had quite some edits in the review queue for (really) old questions (an example would be Partition hidden after installation of linux). While I do think it's not particularly bad to remove the "fluff" from it, I don't really see much value in that edit.
How do you handle it? Am I missing some kind of policy in regard to this? Personally I'd rather reject an edit for old questions that just do minor tweaks like removing a thanks or hi.