@Stijn If "it's the only thing that can be improved" then it probably should not be edited; which is why it was rejected as "too minor". If you "use that reject reason [your]self when there are other obvious issues" then you probably should not use that reason. "too minor" is quite specific. If there are other reasons then maybe "invalid edit" would be more appropriate (I can't just remember what the other reasons are off hand).

@Stijn AFAIK the main reason why it is bad when a "minor edit" is accepted is that it bumps the question to the top of the active queue - which is frustrating to other users who are monitoring this queue for genuine responses and updates. This "frustration" has been vented many times on meta. If this didn't happen for "minor edits" then it probably wouldn't be so bad, but it still unnecessarily pollutes the revision history.

@w3d I understand your point about bumping, this being a smaller site. I mainly use SO, where that isn't an issue. Thanks for the explanation.

@w3d I agree - minor edits do cloud the site given the level of activity on it. That's one of the reasons for my answer here: meta.webmasters.stackexchange.com/questions/1142/…. I still see a lot of these, so perhaps another Meta question to address what's too minor might help?